diff --git a/src/components/editor-page/app-bar/help-button/cheatsheet-line.tsx b/src/components/editor-page/app-bar/help-button/cheatsheet-line.tsx
index 44ffa456b..d9d4a0ba0 100644
--- a/src/components/editor-page/app-bar/help-button/cheatsheet-line.tsx
+++ b/src/components/editor-page/app-bar/help-button/cheatsheet-line.tsx
@@ -4,8 +4,12 @@
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
-import React, { Suspense, useCallback, useMemo } from 'react'
+import React, { Suspense, useEffect, useMemo } from 'react'
 import { WaitSpinner } from '../../../common/wait-spinner/wait-spinner'
+import { eventEmitterContext } from '../../../markdown-renderer/hooks/use-extension-event-emitter'
+import EventEmitter2 from 'eventemitter2'
+import type { TaskCheckedEventPayload } from '../../../../extensions/extra-integrations/task-list/event-emitting-task-list-checkbox'
+import { TaskListCheckboxAppExtension } from '../../../../extensions/extra-integrations/task-list/task-list-checkbox-app-extension'
 
 export interface CheatsheetLineProps {
   markdown: string
@@ -13,7 +17,7 @@ export interface CheatsheetLineProps {
 }
 
 const HighlightedCode = React.lazy(
-  () => import('../../../markdown-renderer/markdown-extension/highlighted-fence/highlighted-code')
+  () => import('../../../../extensions/extra-integrations/highlighted-code-fence/highlighted-code')
 )
 const DocumentMarkdownRenderer = React.lazy(() => import('../../../markdown-renderer/document-markdown-renderer'))
 
@@ -26,12 +30,15 @@ const DocumentMarkdownRenderer = React.lazy(() => import('../../../markdown-rend
  */
 export const CheatsheetLine: React.FC<CheatsheetLineProps> = ({ markdown, onTaskCheckedChange }) => {
   const lines = useMemo(() => markdown.split('\n'), [markdown])
-  const checkboxClick = useCallback(
-    (lineInMarkdown: number, newValue: boolean) => {
-      onTaskCheckedChange(newValue)
-    },
-    [onTaskCheckedChange]
-  )
+  const eventEmitter = useMemo(() => new EventEmitter2(), [])
+
+  useEffect(() => {
+    const handler = ({ checked }: TaskCheckedEventPayload) => onTaskCheckedChange(checked)
+    eventEmitter.on(TaskListCheckboxAppExtension.EVENT_NAME, handler)
+    return () => {
+      eventEmitter.off(TaskListCheckboxAppExtension.EVENT_NAME, handler)
+    }
+  })
 
   return (
     <Suspense
@@ -44,11 +51,9 @@ export const CheatsheetLine: React.FC<CheatsheetLineProps> = ({ markdown, onTask
       }>
       <tr>
         <td>
-          <DocumentMarkdownRenderer
-            markdownContentLines={lines}
-            baseUrl={'https://example.org'}
-            onTaskCheckedChange={checkboxClick}
-          />
+          <eventEmitterContext.Provider value={eventEmitter}>
+            <DocumentMarkdownRenderer markdownContentLines={lines} baseUrl={'https://example.org'} />
+          </eventEmitterContext.Provider>
         </td>
         <td className={'markdown-body'}>
           <HighlightedCode code={markdown} wrapLines={true} startLineNumber={1} language={'markdown'} />
diff --git a/src/components/editor-page/editor-document-renderer/editor-document-renderer.tsx b/src/components/editor-page/editor-document-renderer/editor-document-renderer.tsx
index 70fd0555a..bde90f2ea 100644
--- a/src/components/editor-page/editor-document-renderer/editor-document-renderer.tsx
+++ b/src/components/editor-page/editor-document-renderer/editor-document-renderer.tsx
@@ -11,7 +11,6 @@ import { useTrimmedNoteMarkdownContentWithoutFrontmatter } from '../../../hooks/
 import { NoteType } from '../../../redux/note-details/types/note-details'
 import { useApplicationState } from '../../../hooks/common/use-application-state'
 import { RendererType } from '../../render-page/window-post-message-communicator/rendering-message'
-import { useSetCheckboxInEditor } from './hooks/use-set-checkbox-in-editor'
 import { useOnScrollWithLineOffset } from './hooks/use-on-scroll-with-line-offset'
 import { useScrollStateWithoutLineOffset } from './hooks/use-scroll-state-without-line-offset'
 import { setRendererStatus } from '../../../redux/renderer-status/methods'
@@ -31,7 +30,6 @@ export type EditorDocumentRendererProps = Omit<
 export const EditorDocumentRenderer: React.FC<EditorDocumentRendererProps> = ({ scrollState, onScroll, ...props }) => {
   const trimmedContentLines = useTrimmedNoteMarkdownContentWithoutFrontmatter()
   const noteType: NoteType = useApplicationState((state) => state.noteDetails.frontmatter.type)
-  const setCheckboxInEditor = useSetCheckboxInEditor()
   const adjustedOnScroll = useOnScrollWithLineOffset(onScroll)
   const adjustedScrollState = useScrollStateWithoutLineOffset(scrollState)
 
@@ -40,7 +38,6 @@ export const EditorDocumentRenderer: React.FC<EditorDocumentRendererProps> = ({
       {...props}
       onScroll={adjustedOnScroll}
       scrollState={adjustedScrollState}
-      onTaskCheckedChange={setCheckboxInEditor}
       rendererType={noteType === NoteType.SLIDE ? RendererType.SLIDESHOW : RendererType.DOCUMENT}
       markdownContentLines={trimmedContentLines}
       onRendererStatusChange={setRendererStatus}
diff --git a/src/components/editor-page/editor-page-content.tsx b/src/components/editor-page/editor-page-content.tsx
index 541a61257..4b01d1f84 100644
--- a/src/components/editor-page/editor-page-content.tsx
+++ b/src/components/editor-page/editor-page-content.tsx
@@ -24,6 +24,9 @@ import { NoteAndAppTitleHead } from '../layout/note-and-app-title-head'
 import equal from 'fast-deep-equal'
 import { EditorPane } from './editor-pane/editor-pane'
 import { ChangeEditorContentContextProvider } from './change-content-context/change-content-context'
+import { ExtensionEventEmitterProvider } from '../markdown-renderer/hooks/use-extension-event-emitter'
+import { useComponentsFromAppExtensions } from './editor-pane/hooks/use-components-from-app-extensions'
+import { CommunicatorImageLightbox } from '../markdown-renderer/extensions/image/communicator-image-lightbox'
 
 export enum ScrollSource {
   EDITOR = 'editor',
@@ -124,23 +127,29 @@ export const EditorPageContent: React.FC = () => {
     [onMarkdownRendererScroll, scrollState.rendererScrollState, setRendererToScrollSource]
   )
 
+  const editorExtensionComponents = useComponentsFromAppExtensions()
+
   return (
     <ChangeEditorContentContextProvider>
-      <NoteAndAppTitleHead />
-      <MotdModal />
-      <div className={'d-flex flex-column vh-100'}>
-        <AppBar mode={AppBarMode.EDITOR} />
-        <div className={'flex-fill d-flex h-100 w-100 overflow-hidden flex-row'}>
-          <Splitter
-            showLeft={editorMode === EditorMode.EDITOR || editorMode === EditorMode.BOTH}
-            left={leftPane}
-            showRight={editorMode === EditorMode.PREVIEW || editorMode === EditorMode.BOTH}
-            right={rightPane}
-            additionalContainerClassName={'overflow-hidden'}
-          />
-          <Sidebar />
+      <ExtensionEventEmitterProvider>
+        {editorExtensionComponents}
+        <CommunicatorImageLightbox />
+        <NoteAndAppTitleHead />
+        <MotdModal />
+        <div className={'d-flex flex-column vh-100'}>
+          <AppBar mode={AppBarMode.EDITOR} />
+          <div className={'flex-fill d-flex h-100 w-100 overflow-hidden flex-row'}>
+            <Splitter
+              showLeft={editorMode === EditorMode.EDITOR || editorMode === EditorMode.BOTH}
+              left={leftPane}
+              showRight={editorMode === EditorMode.PREVIEW || editorMode === EditorMode.BOTH}
+              right={rightPane}
+              additionalContainerClassName={'overflow-hidden'}
+            />
+            <Sidebar />
+          </div>
         </div>
-      </div>
+      </ExtensionEventEmitterProvider>
     </ChangeEditorContentContextProvider>
   )
 }
diff --git a/src/components/editor-page/editor-pane/editor-pane.tsx b/src/components/editor-page/editor-pane/editor-pane.tsx
index b101030b4..fda9cc883 100644
--- a/src/components/editor-page/editor-pane/editor-pane.tsx
+++ b/src/components/editor-page/editor-pane/editor-pane.tsx
@@ -21,7 +21,6 @@ import { markdown, markdownLanguage } from '@codemirror/lang-markdown'
 import { EditorView } from '@codemirror/view'
 import { autocompletion } from '@codemirror/autocomplete'
 import { cypressAttribute, cypressId } from '../../../utils/cypress-attribute'
-import { findLanguageByCodeBlockName } from '../../markdown-renderer/markdown-extension/code-block-markdown-extension/find-language-by-code-block-name'
 import { languages } from '@codemirror/language-data'
 import { useCursorActivityCallback } from './hooks/use-cursor-activity-callback'
 import { useCodeMirrorReference, useSetCodeMirrorReference } from '../change-content-context/change-content-context'
@@ -39,12 +38,10 @@ import { useIsConnectionSynced } from './hooks/yjs/use-is-connection-synced'
 import { useMarkdownContentYText } from './hooks/yjs/use-markdown-content-y-text'
 import { lintGutter } from '@codemirror/lint'
 import { useLinter } from './linter/linter'
-import { YoutubeMarkdownExtension } from '../../markdown-renderer/markdown-extension/youtube/youtube-markdown-extension'
-import { VimeoMarkdownExtension } from '../../markdown-renderer/markdown-extension/vimeo/vimeo-markdown-extension'
-import { SequenceDiagramMarkdownExtension } from '../../markdown-renderer/markdown-extension/sequence-diagram/sequence-diagram-markdown-extension'
-import { LegacyShortcodesMarkdownExtension } from '../../markdown-renderer/markdown-extension/legacy-short-codes/legacy-shortcodes-markdown-extension'
 import { FrontmatterLinter } from './linter/frontmatter-linter'
 import { useOnNoteDeleted } from './hooks/yjs/use-on-note-deleted'
+import { findLanguageByCodeBlockName } from '../../markdown-renderer/extensions/base/code-block-markdown-extension/find-language-by-code-block-name'
+import { optionalAppExtensions } from '../../../extensions/extra-integrations/optional-app-extensions'
 
 /**
  * Renders the text editor pane of the editor.
@@ -90,15 +87,9 @@ export const EditorPane: React.FC<ScrollProps> = ({ scrollState, onScroll, onMak
   useInsertNoteContentIntoYTextInMockModeEffect(firstUpdateHappened, websocketConnection)
   const spellCheck = useApplicationState((state) => state.editorConfig.spellCheck)
 
-  // ToDo: Don't initialize new extension array here, instead refactor to global extension array
   const markdownExtensionsLinters = useMemo(() => {
-    return [
-      new YoutubeMarkdownExtension(),
-      new VimeoMarkdownExtension(),
-      new SequenceDiagramMarkdownExtension(),
-      new LegacyShortcodesMarkdownExtension()
-    ]
-      .flatMap((extension) => extension.buildLinter())
+    return optionalAppExtensions
+      .flatMap((extension) => extension.buildCodeMirrorLinter())
       .concat(new FrontmatterLinter())
   }, [])
   const linter = useLinter(markdownExtensionsLinters)
diff --git a/src/components/editor-page/editor-pane/hooks/use-components-from-app-extensions.tsx b/src/components/editor-page/editor-pane/hooks/use-components-from-app-extensions.tsx
new file mode 100644
index 000000000..56386c991
--- /dev/null
+++ b/src/components/editor-page/editor-pane/hooks/use-components-from-app-extensions.tsx
@@ -0,0 +1,24 @@
+/*
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import type { ReactElement } from 'react'
+import React, { Fragment, useMemo } from 'react'
+import { optionalAppExtensions } from '../../../../extensions/extra-integrations/optional-app-extensions'
+
+/**
+ * Generator react elements for components that are generated by the used {@link AppExtension app extensions}.
+ */
+export const useComponentsFromAppExtensions = (): ReactElement => {
+  return useMemo(() => {
+    return (
+      <Fragment key={'app-extensions'}>
+        {optionalAppExtensions.map((extension, index) =>
+          React.createElement(extension.buildEditorExtensionComponent(), { key: index })
+        )}
+      </Fragment>
+    )
+  }, [])
+}
diff --git a/src/components/editor-page/renderer-pane/communicator-image-lightbox.tsx b/src/components/editor-page/renderer-pane/communicator-image-lightbox.tsx
deleted file mode 100644
index 41759de4c..000000000
--- a/src/components/editor-page/renderer-pane/communicator-image-lightbox.tsx
+++ /dev/null
@@ -1,44 +0,0 @@
-/*
- * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
- *
- * SPDX-License-Identifier: AGPL-3.0-only
- */
-
-import React, { useCallback, useState } from 'react'
-import { ImageLightboxModal } from '../../markdown-renderer/markdown-extension/image/image-lightbox-modal'
-import type {
-  ImageClickedMessage,
-  ImageDetails
-} from '../../render-page/window-post-message-communicator/rendering-message'
-import { CommunicationMessageType } from '../../render-page/window-post-message-communicator/rendering-message'
-import { useEditorReceiveHandler } from '../../render-page/window-post-message-communicator/hooks/use-editor-receive-handler'
-import { useBooleanState } from '../../../hooks/common/use-boolean-state'
-
-/**
- * Handles messages from the render in the iframe to open a {@link ImageLightboxModal}.
- */
-export const CommunicatorImageLightbox: React.FC = () => {
-  const [lightboxDetails, setLightboxDetails] = useState<ImageDetails | undefined>(undefined)
-  const [modalVisibility, showModal, closeModal] = useBooleanState()
-
-  useEditorReceiveHandler(
-    CommunicationMessageType.IMAGE_CLICKED,
-    useCallback(
-      (values: ImageClickedMessage) => {
-        setLightboxDetails?.(values.details)
-        showModal()
-      },
-      [showModal]
-    )
-  )
-
-  return (
-    <ImageLightboxModal
-      show={modalVisibility}
-      onHide={closeModal}
-      src={lightboxDetails?.src}
-      alt={lightboxDetails?.alt}
-      title={lightboxDetails?.title}
-    />
-  )
-}
diff --git a/src/components/editor-page/renderer-pane/render-iframe.tsx b/src/components/editor-page/renderer-pane/render-iframe.tsx
index e48592937..53cce6448 100644
--- a/src/components/editor-page/renderer-pane/render-iframe.tsx
+++ b/src/components/editor-page/renderer-pane/render-iframe.tsx
@@ -3,20 +3,19 @@
  *
  * SPDX-License-Identifier: AGPL-3.0-only
  */
-import React, { Fragment, useCallback, useEffect, useRef, useState } from 'react'
+import React, { Fragment, useCallback, useEffect, useMemo, useRef, useState } from 'react'
 import { isTestMode } from '../../../utils/test-modes'
 import type { RendererProps } from '../../render-page/markdown-document'
 import type {
+  ExtensionEvent,
   OnFirstHeadingChangeMessage,
   OnHeightChangeMessage,
-  OnTaskCheckboxChangeMessage,
   RendererType,
   SetScrollStateMessage
 } from '../../render-page/window-post-message-communicator/rendering-message'
 import { CommunicationMessageType } from '../../render-page/window-post-message-communicator/rendering-message'
 import { useEditorToRendererCommunicator } from '../render-context/editor-to-renderer-communicator-context-provider'
 import { useForceRenderPageUrlOnIframeLoadCallback } from './hooks/use-force-render-page-url-on-iframe-load-callback'
-import { CommunicatorImageLightbox } from './communicator-image-lightbox'
 import { useEditorReceiveHandler } from '../../render-page/window-post-message-communicator/hooks/use-editor-receive-handler'
 import { useSendDarkModeStatusToRenderer } from './hooks/use-send-dark-mode-status-to-renderer'
 import { useSendMarkdownToRenderer } from './hooks/use-send-markdown-to-renderer'
@@ -24,10 +23,10 @@ import { useSendScrollState } from './hooks/use-send-scroll-state'
 import { Logger } from '../../../utils/logger'
 import { useEffectOnRenderTypeChange } from './hooks/use-effect-on-render-type-change'
 import { cypressAttribute, cypressId } from '../../../utils/cypress-attribute'
-import { getGlobalState } from '../../../redux'
 import { ORIGIN, useBaseUrl } from '../../../hooks/common/use-base-url'
 import { ShowIf } from '../../common/show-if/show-if'
 import { WaitSpinner } from '../../common/wait-spinner/wait-spinner'
+import { useExtensionEventEmitter } from '../../markdown-renderer/hooks/use-extension-event-emitter'
 
 export interface RenderIframeProps extends RendererProps {
   rendererType: RendererType
@@ -58,7 +57,6 @@ const log = new Logger('RenderIframe')
  */
 export const RenderIframe: React.FC<RenderIframeProps> = ({
   markdownContentLines,
-  onTaskCheckedChange,
   scrollState,
   onFirstHeadingChange,
   onScroll,
@@ -92,6 +90,10 @@ export const RenderIframe: React.FC<RenderIframeProps> = ({
     }
   }, [iframeCommunicator, rendererReady])
 
+  useEffect(() => {
+    onRendererStatusChange?.(rendererReady)
+  }, [onRendererStatusChange, rendererReady])
+
   useEditorReceiveHandler(
     CommunicationMessageType.ON_FIRST_HEADING_CHANGE,
     useCallback(
@@ -105,15 +107,15 @@ export const RenderIframe: React.FC<RenderIframeProps> = ({
     useCallback(() => onMakeScrollSource?.(), [onMakeScrollSource])
   )
 
+  const eventEmitter = useExtensionEventEmitter()
+
   useEditorReceiveHandler(
-    CommunicationMessageType.ON_TASK_CHECKBOX_CHANGE,
-    useCallback(
-      (values: OnTaskCheckboxChangeMessage) => {
-        const lineOffset = getGlobalState().noteDetails.frontmatterRendererInfo.lineOffset
-        onTaskCheckedChange?.(values.lineInMarkdown + lineOffset, values.checked)
-      },
-      [onTaskCheckedChange]
-    )
+    CommunicationMessageType.EXTENSION_EVENT,
+    useMemo(() => {
+      return eventEmitter === undefined
+        ? undefined
+        : (values: ExtensionEvent) => eventEmitter.emit(values.eventName, values.payload)
+    }, [eventEmitter])
   )
 
   useEditorReceiveHandler(
@@ -169,7 +171,6 @@ export const RenderIframe: React.FC<RenderIframeProps> = ({
 
   return (
     <Fragment>
-      <CommunicatorImageLightbox />
       <ShowIf condition={!rendererReady}>
         <WaitSpinner />
       </ShowIf>
diff --git a/src/components/editor-page/synced-scroll/utils.ts b/src/components/editor-page/synced-scroll/utils.ts
index e79359757..2ddb38d71 100644
--- a/src/components/editor-page/synced-scroll/utils.ts
+++ b/src/components/editor-page/synced-scroll/utils.ts
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
-import type { LineMarkerPosition } from '../../markdown-renderer/markdown-extension/linemarker/types'
+import type { LineMarkerPosition } from '../../markdown-renderer/extensions/linemarker/types'
 
 /**
  * Finds the {@link LineMarkerPosition line markers} from a list of given line markers that are the closest to the given line number.
diff --git a/src/components/editor-page/table-of-contents/use-build-react-dom-from-toc-ast.tsx b/src/components/editor-page/table-of-contents/use-build-react-dom-from-toc-ast.tsx
index c0e30c8f9..9cb80cf66 100644
--- a/src/components/editor-page/table-of-contents/use-build-react-dom-from-toc-ast.tsx
+++ b/src/components/editor-page/table-of-contents/use-build-react-dom-from-toc-ast.tsx
@@ -9,7 +9,7 @@ import type { ReactElement } from 'react'
 import React, { Fragment, useMemo } from 'react'
 import { ShowIf } from '../../common/show-if/show-if'
 import { tocSlugify } from './toc-slugify'
-import { JumpAnchor } from '../../markdown-renderer/markdown-extension/link-replacer/jump-anchor'
+import { JumpAnchor } from '../../markdown-renderer/extensions/link-replacer/jump-anchor'
 
 /**
  * Generates a React DOM part for the table of contents from the given AST of the document.
diff --git a/src/components/markdown-renderer/common-markdown-renderer-props.ts b/src/components/markdown-renderer/common-markdown-renderer-props.ts
index 3fb9190cb..84f25ba23 100644
--- a/src/components/markdown-renderer/common-markdown-renderer-props.ts
+++ b/src/components/markdown-renderer/common-markdown-renderer-props.ts
@@ -1,19 +1,14 @@
 /*
- * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
  *
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
-import type { TocAst } from 'markdown-it-toc-done-right'
-import type { ImageClickHandler } from './markdown-extension/image/proxy-image-replacer'
 import type { Ref } from 'react'
 
 export interface CommonMarkdownRendererProps {
   onFirstHeadingChange?: (firstHeading: string | undefined) => void
-  onTaskCheckedChange?: (lineInMarkdown: number, checked: boolean) => void
-  onTocChange?: (ast?: TocAst) => void
   baseUrl: string
-  onImageClick?: ImageClickHandler
   outerContainerRef?: Ref<HTMLDivElement>
   newlinesAreBreaks?: boolean
   lineOffset?: number
diff --git a/src/components/markdown-renderer/document-markdown-renderer.tsx b/src/components/markdown-renderer/document-markdown-renderer.tsx
index 60140d526..da54f047c 100644
--- a/src/components/markdown-renderer/document-markdown-renderer.tsx
+++ b/src/components/markdown-renderer/document-markdown-renderer.tsx
@@ -6,15 +6,15 @@
 
 import React, { useEffect, useMemo, useRef } from 'react'
 import { useConvertMarkdownToReactDom } from './hooks/use-convert-markdown-to-react-dom'
-import type { LineMarkerPosition } from './markdown-extension/linemarker/types'
 import { useTranslation } from 'react-i18next'
-import type { LineMarkers } from './markdown-extension/linemarker/add-line-marker-markdown-it-plugin'
 import { useCalculateLineMarkerPosition } from './utils/calculate-line-marker-positions'
 import { useExtractFirstHeadline } from './hooks/use-extract-first-headline'
 import type { CommonMarkdownRendererProps } from './common-markdown-renderer-props'
 import { useMarkdownExtensions } from './hooks/use-markdown-extensions'
-import { HeadlineAnchorsMarkdownExtension } from './markdown-extension/headline-anchors-markdown-extension'
 import { cypressId } from '../../utils/cypress-attribute'
+import { HeadlineAnchorsMarkdownExtension } from './extensions/headline-anchors-markdown-extension'
+import type { LineMarkerPosition } from './extensions/linemarker/types'
+import type { LineMarkers } from './extensions/linemarker/add-line-marker-markdown-it-plugin'
 
 export interface DocumentMarkdownRendererProps extends CommonMarkdownRendererProps {
   onLineMarkerPositionChanged?: (lineMarkerPosition: LineMarkerPosition[]) => void
@@ -39,10 +39,7 @@ export const DocumentMarkdownRenderer: React.FC<DocumentMarkdownRendererProps> =
   markdownContentLines,
   onFirstHeadingChange,
   onLineMarkerPositionChanged,
-  onTaskCheckedChange,
-  onTocChange,
   baseUrl,
-  onImageClick,
   outerContainerRef,
   newlinesAreBreaks
 }) => {
@@ -52,12 +49,10 @@ export const DocumentMarkdownRenderer: React.FC<DocumentMarkdownRendererProps> =
   const extensions = useMarkdownExtensions(
     baseUrl,
     currentLineMarkers,
-    useMemo(() => [new HeadlineAnchorsMarkdownExtension()], []),
-    onTaskCheckedChange,
-    onImageClick,
-    onTocChange
+    useMemo(() => [new HeadlineAnchorsMarkdownExtension()], [])
   )
-  const markdownReactDom = useConvertMarkdownToReactDom(markdownContentLines, extensions, newlinesAreBreaks)
+
+  const markdownReactDom = useConvertMarkdownToReactDom(markdownContentLines, extensions, newlinesAreBreaks, true)
 
   useTranslation()
   useCalculateLineMarkerPosition(
diff --git a/src/components/markdown-renderer/markdown-extension/code-block-markdown-extension/code-block-markdown-plugin.ts b/src/components/markdown-renderer/extensions/base/code-block-markdown-extension/code-block-markdown-plugin.ts
similarity index 95%
rename from src/components/markdown-renderer/markdown-extension/code-block-markdown-extension/code-block-markdown-plugin.ts
rename to src/components/markdown-renderer/extensions/base/code-block-markdown-extension/code-block-markdown-plugin.ts
index 4f7773b21..b13b5e694 100644
--- a/src/components/markdown-renderer/markdown-extension/code-block-markdown-extension/code-block-markdown-plugin.ts
+++ b/src/components/markdown-renderer/extensions/base/code-block-markdown-extension/code-block-markdown-plugin.ts
@@ -17,7 +17,7 @@ const ruleName = 'code-highlighter'
  * @param state The current state of the processing {@link MarkdownIt} instance.
  * @see MarkdownIt.RuleCore
  */
-const rule: RuleCore = (state) => {
+const rule: RuleCore = (state): void => {
   state.tokens.forEach((token) => {
     if (token.type === 'fence') {
       const highlightInfos = parseCodeBlockParameters(token.info)
@@ -29,7 +29,6 @@ const rule: RuleCore = (state) => {
       )
     }
   })
-  return true
 }
 
 /**
@@ -37,7 +36,7 @@ const rule: RuleCore = (state) => {
  *
  * @param markdownIt The {@link MarkdownIt markdown-it instance} to which the rule should be added
  */
-export const codeBlockMarkdownPlugin: MarkdownIt.PluginSimple = (markdownIt) => {
+export const codeBlockMarkdownPlugin: MarkdownIt.PluginSimple = (markdownIt: MarkdownIt) => {
   if (markdownIt.core.ruler.getRules(ruleName).length === 0) {
     markdownIt.core.ruler.push(ruleName, rule, { alt: [ruleName] })
   }
diff --git a/src/components/markdown-renderer/extensions/base/code-block-markdown-extension/code-block-markdown-renderer-extension.ts b/src/components/markdown-renderer/extensions/base/code-block-markdown-extension/code-block-markdown-renderer-extension.ts
new file mode 100644
index 000000000..a3e4b9788
--- /dev/null
+++ b/src/components/markdown-renderer/extensions/base/code-block-markdown-extension/code-block-markdown-renderer-extension.ts
@@ -0,0 +1,23 @@
+/*
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import type MarkdownIt from 'markdown-it'
+import { codeBlockMarkdownPlugin } from './code-block-markdown-plugin'
+import type { ComponentReplacer } from '../../../replace-components/component-replacer'
+import { MarkdownRendererExtension } from '../markdown-renderer-extension'
+
+/**
+ * A {@link MarkdownRendererExtension markdown extension} that is used for code fence replacements.
+ */
+export abstract class CodeBlockMarkdownRendererExtension extends MarkdownRendererExtension {
+  public configureMarkdownIt(markdownIt: MarkdownIt): void {
+    codeBlockMarkdownPlugin(markdownIt)
+  }
+
+  public buildReplacers(): ComponentReplacer[] {
+    return []
+  }
+}
diff --git a/src/components/markdown-renderer/markdown-extension/code-block-markdown-extension/code-block-parameters.test.ts b/src/components/markdown-renderer/extensions/base/code-block-markdown-extension/code-block-parameters.test.ts
similarity index 100%
rename from src/components/markdown-renderer/markdown-extension/code-block-markdown-extension/code-block-parameters.test.ts
rename to src/components/markdown-renderer/extensions/base/code-block-markdown-extension/code-block-parameters.test.ts
diff --git a/src/components/markdown-renderer/markdown-extension/code-block-markdown-extension/code-block-parameters.ts b/src/components/markdown-renderer/extensions/base/code-block-markdown-extension/code-block-parameters.ts
similarity index 100%
rename from src/components/markdown-renderer/markdown-extension/code-block-markdown-extension/code-block-parameters.ts
rename to src/components/markdown-renderer/extensions/base/code-block-markdown-extension/code-block-parameters.ts
diff --git a/src/components/markdown-renderer/markdown-extension/code-block-markdown-extension/find-language-by-code-block-name.test.ts b/src/components/markdown-renderer/extensions/base/code-block-markdown-extension/find-language-by-code-block-name.test.ts
similarity index 100%
rename from src/components/markdown-renderer/markdown-extension/code-block-markdown-extension/find-language-by-code-block-name.test.ts
rename to src/components/markdown-renderer/extensions/base/code-block-markdown-extension/find-language-by-code-block-name.test.ts
diff --git a/src/components/markdown-renderer/markdown-extension/code-block-markdown-extension/find-language-by-code-block-name.ts b/src/components/markdown-renderer/extensions/base/code-block-markdown-extension/find-language-by-code-block-name.ts
similarity index 100%
rename from src/components/markdown-renderer/markdown-extension/code-block-markdown-extension/find-language-by-code-block-name.ts
rename to src/components/markdown-renderer/extensions/base/code-block-markdown-extension/find-language-by-code-block-name.ts
diff --git a/src/components/markdown-renderer/markdown-extension/markdown-extension.ts b/src/components/markdown-renderer/extensions/base/markdown-renderer-extension.ts
similarity index 68%
rename from src/components/markdown-renderer/markdown-extension/markdown-extension.ts
rename to src/components/markdown-renderer/extensions/base/markdown-renderer-extension.ts
index 0663ee548..6c9b2e6f8 100644
--- a/src/components/markdown-renderer/markdown-extension/markdown-extension.ts
+++ b/src/components/markdown-renderer/extensions/base/markdown-renderer-extension.ts
@@ -4,15 +4,17 @@
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
+import type EventEmitter2 from 'eventemitter2'
 import type MarkdownIt from 'markdown-it'
-import type { NodeProcessor } from '../node-preprocessors/node-processor'
-import type { ComponentReplacer } from '../replace-components/component-replacer'
-import type { Linter } from '../../editor-page/editor-pane/linter/linter'
+import type { NodeProcessor } from '../../node-preprocessors/node-processor'
+import type { ComponentReplacer } from '../../replace-components/component-replacer'
 
 /**
  * Base class for Markdown extensions.
  */
-export abstract class MarkdownExtension {
+export abstract class MarkdownRendererExtension {
+  constructor(protected readonly eventEmitter?: EventEmitter2) {}
+
   // eslint-disable-next-line @typescript-eslint/no-unused-vars
   public configureMarkdownIt(markdownIt: MarkdownIt): void {
     return
@@ -34,8 +36,4 @@ export abstract class MarkdownExtension {
   public buildTagNameAllowList(): string[] {
     return []
   }
-
-  public buildLinter(): Linter[] {
-    return []
-  }
 }
diff --git a/src/components/markdown-renderer/markdown-extension/debugger-markdown-extension.ts b/src/components/markdown-renderer/extensions/debugger-markdown-extension.ts
similarity index 80%
rename from src/components/markdown-renderer/markdown-extension/debugger-markdown-extension.ts
rename to src/components/markdown-renderer/extensions/debugger-markdown-extension.ts
index 883e0b1a2..37c2a5639 100644
--- a/src/components/markdown-renderer/markdown-extension/debugger-markdown-extension.ts
+++ b/src/components/markdown-renderer/extensions/debugger-markdown-extension.ts
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
-import { MarkdownExtension } from './markdown-extension'
+import { MarkdownRendererExtension } from './base/markdown-renderer-extension'
 import type MarkdownIt from 'markdown-it'
 import { Logger } from '../../../utils/logger'
 import { isDevMode } from '../../../utils/test-modes'
@@ -14,7 +14,7 @@ const log = new Logger('DebuggerMarkdownExtension')
 /**
  * Adds console debug logging to the markdown rendering.
  */
-export class DebuggerMarkdownExtension extends MarkdownExtension {
+export class DebuggerMarkdownExtension extends MarkdownRendererExtension {
   public configureMarkdownItPost(markdownIt: MarkdownIt): void {
     if (isDevMode) {
       markdownIt.core.ruler.push('printStateToConsole', (state) => {
diff --git a/src/components/markdown-renderer/markdown-extension/emoji/__snapshots__/emoji-markdown-extension.test.tsx.snap b/src/components/markdown-renderer/extensions/emoji/__snapshots__/emoji-markdown-extension.test.tsx.snap
similarity index 100%
rename from src/components/markdown-renderer/markdown-extension/emoji/__snapshots__/emoji-markdown-extension.test.tsx.snap
rename to src/components/markdown-renderer/extensions/emoji/__snapshots__/emoji-markdown-extension.test.tsx.snap
diff --git a/src/components/markdown-renderer/markdown-extension/emoji/emoji-markdown-extension.test.tsx b/src/components/markdown-renderer/extensions/emoji/emoji-markdown-extension.test.tsx
similarity index 100%
rename from src/components/markdown-renderer/markdown-extension/emoji/emoji-markdown-extension.test.tsx
rename to src/components/markdown-renderer/extensions/emoji/emoji-markdown-extension.test.tsx
diff --git a/src/components/markdown-renderer/markdown-extension/emoji/emoji-markdown-extension.ts b/src/components/markdown-renderer/extensions/emoji/emoji-markdown-extension.ts
similarity index 63%
rename from src/components/markdown-renderer/markdown-extension/emoji/emoji-markdown-extension.ts
rename to src/components/markdown-renderer/extensions/emoji/emoji-markdown-extension.ts
index ae59a02d2..6fd290617 100644
--- a/src/components/markdown-renderer/markdown-extension/emoji/emoji-markdown-extension.ts
+++ b/src/components/markdown-renderer/extensions/emoji/emoji-markdown-extension.ts
@@ -1,10 +1,10 @@
 /*
- * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
  *
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
-import { MarkdownExtension } from '../markdown-extension'
+import { MarkdownRendererExtension } from '../base/markdown-renderer-extension'
 import type MarkdownIt from 'markdown-it'
 import emoji from 'markdown-it-emoji/bare'
 import { combinedEmojiData } from './mapping'
@@ -12,7 +12,7 @@ import { combinedEmojiData } from './mapping'
 /**
  * Adds support for utf-8 emojis.
  */
-export class EmojiMarkdownExtension extends MarkdownExtension {
+export class EmojiMarkdownExtension extends MarkdownRendererExtension {
   public configureMarkdownIt(markdownIt: MarkdownIt): void {
     markdownIt.use(emoji, {
       defs: combinedEmojiData
diff --git a/src/components/markdown-renderer/markdown-extension/emoji/mapping.ts b/src/components/markdown-renderer/extensions/emoji/mapping.ts
similarity index 95%
rename from src/components/markdown-renderer/markdown-extension/emoji/mapping.ts
rename to src/components/markdown-renderer/extensions/emoji/mapping.ts
index cfedfd466..b545202cf 100644
--- a/src/components/markdown-renderer/markdown-extension/emoji/mapping.ts
+++ b/src/components/markdown-renderer/extensions/emoji/mapping.ts
@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
  *
  * SPDX-License-Identifier: AGPL-3.0-only
  */
diff --git a/src/components/markdown-renderer/markdown-extension/generic-syntax-markdown-extension.ts b/src/components/markdown-renderer/extensions/generic-syntax-markdown-extension.ts
similarity index 84%
rename from src/components/markdown-renderer/markdown-extension/generic-syntax-markdown-extension.ts
rename to src/components/markdown-renderer/extensions/generic-syntax-markdown-extension.ts
index 8fde99fb5..3ea349a44 100644
--- a/src/components/markdown-renderer/markdown-extension/generic-syntax-markdown-extension.ts
+++ b/src/components/markdown-renderer/extensions/generic-syntax-markdown-extension.ts
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
-import { MarkdownExtension } from './markdown-extension'
+import { MarkdownRendererExtension } from './base/markdown-renderer-extension'
 import type MarkdownIt from 'markdown-it'
 import abbreviation from 'markdown-it-abbr'
 import definitionList from 'markdown-it-deflist'
@@ -18,7 +18,7 @@ import { imageSize } from '@hedgedoc/markdown-it-image-size'
 /**
  * Adds some common markdown syntaxes to the markdown rendering.
  */
-export class GenericSyntaxMarkdownExtension extends MarkdownExtension {
+export class GenericSyntaxMarkdownExtension extends MarkdownRendererExtension {
   public configureMarkdownIt(markdownIt: MarkdownIt): void {
     abbreviation(markdownIt)
     definitionList(markdownIt)
diff --git a/src/components/markdown-renderer/markdown-extension/headline-anchors-markdown-extension.ts b/src/components/markdown-renderer/extensions/headline-anchors-markdown-extension.ts
similarity index 78%
rename from src/components/markdown-renderer/markdown-extension/headline-anchors-markdown-extension.ts
rename to src/components/markdown-renderer/extensions/headline-anchors-markdown-extension.ts
index 554ce2c83..8f0917f68 100644
--- a/src/components/markdown-renderer/markdown-extension/headline-anchors-markdown-extension.ts
+++ b/src/components/markdown-renderer/extensions/headline-anchors-markdown-extension.ts
@@ -4,14 +4,14 @@
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
-import { MarkdownExtension } from './markdown-extension'
+import { MarkdownRendererExtension } from './base/markdown-renderer-extension'
 import type MarkdownIt from 'markdown-it'
 import anchor from 'markdown-it-anchor'
 
 /**
  * Adds headline anchors to the markdown rendering.
  */
-export class HeadlineAnchorsMarkdownExtension extends MarkdownExtension {
+export class HeadlineAnchorsMarkdownExtension extends MarkdownRendererExtension {
   public configureMarkdownIt(markdownIt: MarkdownIt): void {
     anchor(markdownIt, {
       permalink: anchor.permalink.ariaHidden({
diff --git a/src/components/markdown-renderer/markdown-extension/iframe-capsule/iframe-capsule-markdown-extension.ts b/src/components/markdown-renderer/extensions/iframe-capsule/iframe-capsule-markdown-extension.ts
similarity index 76%
rename from src/components/markdown-renderer/markdown-extension/iframe-capsule/iframe-capsule-markdown-extension.ts
rename to src/components/markdown-renderer/extensions/iframe-capsule/iframe-capsule-markdown-extension.ts
index efcbe42ae..c8059c4d7 100644
--- a/src/components/markdown-renderer/markdown-extension/iframe-capsule/iframe-capsule-markdown-extension.ts
+++ b/src/components/markdown-renderer/extensions/iframe-capsule/iframe-capsule-markdown-extension.ts
@@ -4,14 +4,14 @@
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
-import { MarkdownExtension } from '../markdown-extension'
+import { MarkdownRendererExtension } from '../base/markdown-renderer-extension'
 import type { ComponentReplacer } from '../../replace-components/component-replacer'
 import { IframeCapsuleReplacer } from './iframe-capsule-replacer'
 
 /**
  * Adds a replacer that capsules iframes in a click shield.
  */
-export class IframeCapsuleMarkdownExtension extends MarkdownExtension {
+export class IframeCapsuleMarkdownExtension extends MarkdownRendererExtension {
   public buildReplacers(): ComponentReplacer[] {
     return [new IframeCapsuleReplacer()]
   }
diff --git a/src/components/markdown-renderer/markdown-extension/iframe-capsule/iframe-capsule-replacer.tsx b/src/components/markdown-renderer/extensions/iframe-capsule/iframe-capsule-replacer.tsx
similarity index 100%
rename from src/components/markdown-renderer/markdown-extension/iframe-capsule/iframe-capsule-replacer.tsx
rename to src/components/markdown-renderer/extensions/iframe-capsule/iframe-capsule-replacer.tsx
diff --git a/src/components/markdown-renderer/markdown-extension/image-placeholder/add-line-to-placeholder-image-tags.ts b/src/components/markdown-renderer/extensions/image-placeholder/add-line-to-placeholder-image-tags.ts
similarity index 94%
rename from src/components/markdown-renderer/markdown-extension/image-placeholder/add-line-to-placeholder-image-tags.ts
rename to src/components/markdown-renderer/extensions/image-placeholder/add-line-to-placeholder-image-tags.ts
index 4cc801294..346ce5cc4 100644
--- a/src/components/markdown-renderer/markdown-extension/image-placeholder/add-line-to-placeholder-image-tags.ts
+++ b/src/components/markdown-renderer/extensions/image-placeholder/add-line-to-placeholder-image-tags.ts
@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
  *
  * SPDX-License-Identifier: AGPL-3.0-only
  */
diff --git a/src/components/markdown-renderer/markdown-extension/image-placeholder/hooks/use-on-image-upload.ts b/src/components/markdown-renderer/extensions/image-placeholder/hooks/use-on-image-upload.ts
similarity index 100%
rename from src/components/markdown-renderer/markdown-extension/image-placeholder/hooks/use-on-image-upload.ts
rename to src/components/markdown-renderer/extensions/image-placeholder/hooks/use-on-image-upload.ts
diff --git a/src/components/markdown-renderer/markdown-extension/image-placeholder/hooks/use-placeholder-size-style.ts b/src/components/markdown-renderer/extensions/image-placeholder/hooks/use-placeholder-size-style.ts
similarity index 92%
rename from src/components/markdown-renderer/markdown-extension/image-placeholder/hooks/use-placeholder-size-style.ts
rename to src/components/markdown-renderer/extensions/image-placeholder/hooks/use-placeholder-size-style.ts
index 3ca8c26c7..4cbb0606d 100644
--- a/src/components/markdown-renderer/markdown-extension/image-placeholder/hooks/use-placeholder-size-style.ts
+++ b/src/components/markdown-renderer/extensions/image-placeholder/hooks/use-placeholder-size-style.ts
@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
  *
  * SPDX-License-Identifier: AGPL-3.0-only
  */
diff --git a/src/components/markdown-renderer/markdown-extension/image-placeholder/image-placeholder-markdown-extension.ts b/src/components/markdown-renderer/extensions/image-placeholder/image-placeholder-markdown-extension.ts
similarity index 82%
rename from src/components/markdown-renderer/markdown-extension/image-placeholder/image-placeholder-markdown-extension.ts
rename to src/components/markdown-renderer/extensions/image-placeholder/image-placeholder-markdown-extension.ts
index 3ebd11418..6fb815362 100644
--- a/src/components/markdown-renderer/markdown-extension/image-placeholder/image-placeholder-markdown-extension.ts
+++ b/src/components/markdown-renderer/extensions/image-placeholder/image-placeholder-markdown-extension.ts
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
-import { MarkdownExtension } from '../markdown-extension'
+import { MarkdownRendererExtension } from '../base/markdown-renderer-extension'
 import { addLineToPlaceholderImageTags } from './add-line-to-placeholder-image-tags'
 import type MarkdownIt from 'markdown-it/lib'
 import type { ComponentReplacer } from '../../replace-components/component-replacer'
@@ -13,7 +13,7 @@ import { ImagePlaceholderReplacer } from './image-placeholder-replacer'
 /**
  * Adds support for {@link ImagePlaceholder}.
  */
-export class ImagePlaceholderMarkdownExtension extends MarkdownExtension {
+export class ImagePlaceholderMarkdownExtension extends MarkdownRendererExtension {
   public static readonly PLACEHOLDER_URL = 'https://'
 
   constructor() {
diff --git a/src/components/markdown-renderer/markdown-extension/image-placeholder/image-placeholder-replacer.tsx b/src/components/markdown-renderer/extensions/image-placeholder/image-placeholder-replacer.tsx
similarity index 51%
rename from src/components/markdown-renderer/markdown-extension/image-placeholder/image-placeholder-replacer.tsx
rename to src/components/markdown-renderer/extensions/image-placeholder/image-placeholder-replacer.tsx
index f7b2556f0..3dac78387 100644
--- a/src/components/markdown-renderer/markdown-extension/image-placeholder/image-placeholder-replacer.tsx
+++ b/src/components/markdown-renderer/extensions/image-placeholder/image-placeholder-replacer.tsx
@@ -1,11 +1,11 @@
 /*
- * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
  *
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
 import type { NodeReplacement } from '../../replace-components/component-replacer'
-import { ComponentReplacer } from '../../replace-components/component-replacer'
+import { ComponentReplacer, DO_NOT_REPLACE } from '../../replace-components/component-replacer'
 import type { Element } from 'domhandler'
 import { ImagePlaceholder } from './image-placeholder'
 import { ImagePlaceholderMarkdownExtension } from './image-placeholder-markdown-extension'
@@ -25,20 +25,21 @@ export class ImagePlaceholderReplacer extends ComponentReplacer {
   }
 
   replace(node: Element): NodeReplacement {
-    if (node.name === 'img' && node.attribs && node.attribs.src === ImagePlaceholderMarkdownExtension.PLACEHOLDER_URL) {
-      const lineIndex = Number(node.attribs['data-line'])
-      const indexInLine = this.countPerSourceLine.get(lineIndex) ?? 0
-      this.countPerSourceLine.set(lineIndex, indexInLine + 1)
-      return (
-        <ImagePlaceholder
-          alt={node.attribs.alt}
-          title={node.attribs.title}
-          width={node.attribs.width}
-          height={node.attribs.height}
-          lineIndex={isNaN(lineIndex) ? undefined : lineIndex}
-          placeholderIndexInLine={indexInLine}
-        />
-      )
+    if (node.name !== 'img' || node.attribs?.src !== ImagePlaceholderMarkdownExtension.PLACEHOLDER_URL) {
+      return DO_NOT_REPLACE
     }
+    const lineIndex = Number(node.attribs['data-line'])
+    const indexInLine = this.countPerSourceLine.get(lineIndex) ?? 0
+    this.countPerSourceLine.set(lineIndex, indexInLine + 1)
+    return (
+      <ImagePlaceholder
+        alt={node.attribs.alt}
+        title={node.attribs.title}
+        width={node.attribs.width}
+        height={node.attribs.height}
+        lineIndex={isNaN(lineIndex) ? undefined : lineIndex}
+        placeholderIndexInLine={indexInLine}
+      />
+    )
   }
 }
diff --git a/src/components/markdown-renderer/markdown-extension/image-placeholder/image-placeholder.module.scss b/src/components/markdown-renderer/extensions/image-placeholder/image-placeholder.module.scss
similarity index 88%
rename from src/components/markdown-renderer/markdown-extension/image-placeholder/image-placeholder.module.scss
rename to src/components/markdown-renderer/extensions/image-placeholder/image-placeholder.module.scss
index 015eeffc9..1f12e0565 100644
--- a/src/components/markdown-renderer/markdown-extension/image-placeholder/image-placeholder.module.scss
+++ b/src/components/markdown-renderer/extensions/image-placeholder/image-placeholder.module.scss
@@ -1,5 +1,5 @@
-/*
- * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+/*!
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
  *
  * SPDX-License-Identifier: AGPL-3.0-only
  */
diff --git a/src/components/markdown-renderer/markdown-extension/image-placeholder/image-placeholder.tsx b/src/components/markdown-renderer/extensions/image-placeholder/image-placeholder.tsx
similarity index 98%
rename from src/components/markdown-renderer/markdown-extension/image-placeholder/image-placeholder.tsx
rename to src/components/markdown-renderer/extensions/image-placeholder/image-placeholder.tsx
index e522992b0..9b7b964a8 100644
--- a/src/components/markdown-renderer/markdown-extension/image-placeholder/image-placeholder.tsx
+++ b/src/components/markdown-renderer/extensions/image-placeholder/image-placeholder.tsx
@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
  *
  * SPDX-License-Identifier: AGPL-3.0-only
  */
diff --git a/src/components/markdown-renderer/markdown-extension/image-placeholder/utils/build-placeholder-size-css.test.ts b/src/components/markdown-renderer/extensions/image-placeholder/utils/build-placeholder-size-css.test.ts
similarity index 97%
rename from src/components/markdown-renderer/markdown-extension/image-placeholder/utils/build-placeholder-size-css.test.ts
rename to src/components/markdown-renderer/extensions/image-placeholder/utils/build-placeholder-size-css.test.ts
index cb467ccb7..02836dd2a 100644
--- a/src/components/markdown-renderer/markdown-extension/image-placeholder/utils/build-placeholder-size-css.test.ts
+++ b/src/components/markdown-renderer/extensions/image-placeholder/utils/build-placeholder-size-css.test.ts
@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
  *
  * SPDX-License-Identifier: AGPL-3.0-only
  */
diff --git a/src/components/markdown-renderer/markdown-extension/image-placeholder/utils/build-placeholder-size-css.ts b/src/components/markdown-renderer/extensions/image-placeholder/utils/build-placeholder-size-css.ts
similarity index 96%
rename from src/components/markdown-renderer/markdown-extension/image-placeholder/utils/build-placeholder-size-css.ts
rename to src/components/markdown-renderer/extensions/image-placeholder/utils/build-placeholder-size-css.ts
index 2621e6c12..26caddbd0 100644
--- a/src/components/markdown-renderer/markdown-extension/image-placeholder/utils/build-placeholder-size-css.ts
+++ b/src/components/markdown-renderer/extensions/image-placeholder/utils/build-placeholder-size-css.ts
@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
  *
  * SPDX-License-Identifier: AGPL-3.0-only
  */
diff --git a/src/components/markdown-renderer/extensions/image/communicator-image-lightbox.tsx b/src/components/markdown-renderer/extensions/image/communicator-image-lightbox.tsx
new file mode 100644
index 000000000..3e0f211f7
--- /dev/null
+++ b/src/components/markdown-renderer/extensions/image/communicator-image-lightbox.tsx
@@ -0,0 +1,40 @@
+/*
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import type { ImageDetails } from '../../../render-page/window-post-message-communicator/rendering-message'
+import React, { useCallback, useState } from 'react'
+import { useBooleanState } from '../../../../hooks/common/use-boolean-state'
+import { ImageLightboxModal } from './image-lightbox-modal'
+import { useExtensionEventEmitterHandler } from '../../hooks/use-extension-event-emitter'
+import { SHOW_IMAGE_LIGHTBOX_EVENT_NAME } from './event-emitting-proxy-image-frame'
+
+/**
+ * Handles messages from the render in the iframe to open a {@link ImageLightboxModal}.
+ */
+export const CommunicatorImageLightbox: React.FC = () => {
+  const [lightboxDetails, setLightboxDetails] = useState<ImageDetails | undefined>(undefined)
+  const [modalVisibility, showModal, closeModal] = useBooleanState()
+
+  const handler = useCallback(
+    (values: ImageDetails) => {
+      setLightboxDetails?.(values)
+      showModal()
+    },
+    [showModal]
+  )
+
+  useExtensionEventEmitterHandler(SHOW_IMAGE_LIGHTBOX_EVENT_NAME, handler)
+
+  return (
+    <ImageLightboxModal
+      show={modalVisibility}
+      onHide={closeModal}
+      src={lightboxDetails?.src}
+      alt={lightboxDetails?.alt}
+      title={lightboxDetails?.title}
+    />
+  )
+}
diff --git a/src/components/markdown-renderer/extensions/image/event-emitting-proxy-image-frame.tsx b/src/components/markdown-renderer/extensions/image/event-emitting-proxy-image-frame.tsx
new file mode 100644
index 000000000..dea8cf046
--- /dev/null
+++ b/src/components/markdown-renderer/extensions/image/event-emitting-proxy-image-frame.tsx
@@ -0,0 +1,40 @@
+/*
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import React, { useCallback } from 'react'
+import { useExtensionEventEmitter } from '../../hooks/use-extension-event-emitter'
+import { ProxyImageFrame } from './proxy-image-frame'
+import type { ImageDetails } from '../../../render-page/window-post-message-communicator/rendering-message'
+
+type EventEmittingProxyImageFrameProps = Omit<React.ImgHTMLAttributes<HTMLImageElement>, 'onClick'>
+
+export const SHOW_IMAGE_LIGHTBOX_EVENT_NAME = 'ImageClick'
+
+/**
+ * Renders a {@link ProxyImageFrame} but claims the `onClick` event to send image information to the current event emitter.
+ *
+ * @param props props that will be forwarded to the inner image frame
+ */
+export const EventEmittingProxyImageFrame: React.FC<EventEmittingProxyImageFrameProps> = (props) => {
+  const eventEmitter = useExtensionEventEmitter()
+
+  const onClick = useCallback(
+    (event: React.MouseEvent<HTMLImageElement, MouseEvent>) => {
+      const image = event.target as HTMLImageElement
+      if (image.src === '') {
+        return
+      }
+      eventEmitter?.emit(SHOW_IMAGE_LIGHTBOX_EVENT_NAME, {
+        src: image.src,
+        alt: image.alt,
+        title: image.title
+      } as ImageDetails)
+    },
+    [eventEmitter]
+  )
+
+  return <ProxyImageFrame {...props} onClick={onClick} />
+}
diff --git a/src/components/markdown-renderer/markdown-extension/image/image-lightbox-modal.tsx b/src/components/markdown-renderer/extensions/image/image-lightbox-modal.tsx
similarity index 100%
rename from src/components/markdown-renderer/markdown-extension/image/image-lightbox-modal.tsx
rename to src/components/markdown-renderer/extensions/image/image-lightbox-modal.tsx
diff --git a/src/components/markdown-renderer/markdown-extension/image/lightbox.module.scss b/src/components/markdown-renderer/extensions/image/lightbox.module.scss
similarity index 72%
rename from src/components/markdown-renderer/markdown-extension/image/lightbox.module.scss
rename to src/components/markdown-renderer/extensions/image/lightbox.module.scss
index 3b84927c2..be12a7024 100644
--- a/src/components/markdown-renderer/markdown-extension/image/lightbox.module.scss
+++ b/src/components/markdown-renderer/extensions/image/lightbox.module.scss
@@ -1,5 +1,5 @@
-/*
- * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+/*!
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
  *
  * SPDX-License-Identifier: AGPL-3.0-only
  */
diff --git a/src/components/markdown-renderer/markdown-extension/image/proxy-image-frame.tsx b/src/components/markdown-renderer/extensions/image/proxy-image-frame.tsx
similarity index 96%
rename from src/components/markdown-renderer/markdown-extension/image/proxy-image-frame.tsx
rename to src/components/markdown-renderer/extensions/image/proxy-image-frame.tsx
index d94303578..3ba9a211f 100644
--- a/src/components/markdown-renderer/markdown-extension/image/proxy-image-frame.tsx
+++ b/src/components/markdown-renderer/extensions/image/proxy-image-frame.tsx
@@ -32,7 +32,7 @@ export const ProxyImageFrame: React.FC<React.ImgHTMLAttributes<HTMLImageElement>
       .catch((err) => log.error(err))
   }, [imageProxyEnabled, src])
 
-  // The next image processor works with a whitelist of origins. Therefore we can't use it for general images.
+  // The next image processor works with a whitelist of origins. Therefore, we can't use it for general images.
   // eslint-disable-next-line @next/next/no-img-element
   return <img src={imageProxyEnabled ? imageUrl : src ?? ''} title={title ?? alt ?? ''} alt={alt} {...props} />
 }
diff --git a/src/components/markdown-renderer/extensions/image/proxy-image-markdown-extension.ts b/src/components/markdown-renderer/extensions/image/proxy-image-markdown-extension.ts
new file mode 100644
index 000000000..8c43ef65b
--- /dev/null
+++ b/src/components/markdown-renderer/extensions/image/proxy-image-markdown-extension.ts
@@ -0,0 +1,18 @@
+/*
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import { MarkdownRendererExtension } from '../base/markdown-renderer-extension'
+import type { ComponentReplacer } from '../../replace-components/component-replacer'
+import { ProxyImageReplacer } from './proxy-image-replacer'
+
+/**
+ * Adds support for image lightbox and image proxy redirection.
+ */
+export class ProxyImageMarkdownExtension extends MarkdownRendererExtension {
+  buildReplacers(): ComponentReplacer[] {
+    return [new ProxyImageReplacer()]
+  }
+}
diff --git a/src/components/markdown-renderer/markdown-extension/image/proxy-image-replacer.tsx b/src/components/markdown-renderer/extensions/image/proxy-image-replacer.tsx
similarity index 78%
rename from src/components/markdown-renderer/markdown-extension/image/proxy-image-replacer.tsx
rename to src/components/markdown-renderer/extensions/image/proxy-image-replacer.tsx
index e37c8c717..9a4cbc7f7 100644
--- a/src/components/markdown-renderer/markdown-extension/image/proxy-image-replacer.tsx
+++ b/src/components/markdown-renderer/extensions/image/proxy-image-replacer.tsx
@@ -8,7 +8,7 @@ import type { Element } from 'domhandler'
 import React from 'react'
 import type { NodeReplacement } from '../../replace-components/component-replacer'
 import { ComponentReplacer, DO_NOT_REPLACE } from '../../replace-components/component-replacer'
-import { ProxyImageFrame } from './proxy-image-frame'
+import { EventEmittingProxyImageFrame } from './event-emitting-proxy-image-frame'
 
 export type ImageClickHandler = (event: React.MouseEvent<HTMLImageElement, MouseEvent>) => void
 
@@ -16,18 +16,11 @@ export type ImageClickHandler = (event: React.MouseEvent<HTMLImageElement, Mouse
  * Detects image tags and loads them via image proxy if configured.
  */
 export class ProxyImageReplacer extends ComponentReplacer {
-  private readonly clickHandler?: ImageClickHandler
-
-  constructor(clickHandler?: ImageClickHandler) {
-    super()
-    this.clickHandler = clickHandler
-  }
-
   public replace(node: Element): NodeReplacement {
     return node.name !== 'img' ? (
       DO_NOT_REPLACE
     ) : (
-      <ProxyImageFrame
+      <EventEmittingProxyImageFrame
         id={node.attribs.id}
         className={`${node.attribs.class} cursor-zoom-in`}
         src={node.attribs.src}
@@ -35,7 +28,6 @@ export class ProxyImageReplacer extends ComponentReplacer {
         title={node.attribs.title}
         width={node.attribs.width}
         height={node.attribs.height}
-        onClick={this.clickHandler}
       />
     )
   }
diff --git a/src/components/markdown-renderer/markdown-extension/linemarker/add-line-marker-markdown-it-plugin.ts b/src/components/markdown-renderer/extensions/linemarker/add-line-marker-markdown-it-plugin.ts
similarity index 100%
rename from src/components/markdown-renderer/markdown-extension/linemarker/add-line-marker-markdown-it-plugin.ts
rename to src/components/markdown-renderer/extensions/linemarker/add-line-marker-markdown-it-plugin.ts
diff --git a/src/components/markdown-renderer/markdown-extension/linemarker/linemarker-markdown-extension.ts b/src/components/markdown-renderer/extensions/linemarker/linemarker-markdown-extension.ts
similarity index 86%
rename from src/components/markdown-renderer/markdown-extension/linemarker/linemarker-markdown-extension.ts
rename to src/components/markdown-renderer/extensions/linemarker/linemarker-markdown-extension.ts
index e139824a4..013ad2e0c 100644
--- a/src/components/markdown-renderer/markdown-extension/linemarker/linemarker-markdown-extension.ts
+++ b/src/components/markdown-renderer/extensions/linemarker/linemarker-markdown-extension.ts
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
-import { MarkdownExtension } from '../markdown-extension'
+import { MarkdownRendererExtension } from '../base/markdown-renderer-extension'
 import { LinemarkerReplacer } from './linemarker-replacer'
 import type { ComponentReplacer } from '../../replace-components/component-replacer'
 import type { LineMarkers } from './add-line-marker-markdown-it-plugin'
@@ -14,7 +14,7 @@ import type MarkdownIt from 'markdown-it'
 /**
  * Adds support for the generation of line marker elements which are needed for synced scrolling.
  */
-export class LinemarkerMarkdownExtension extends MarkdownExtension {
+export class LinemarkerMarkdownExtension extends MarkdownRendererExtension {
   public static readonly tagName = 'app-linemarker'
 
   constructor(private onLineMarkers?: (lineMarkers: LineMarkers[]) => void) {
diff --git a/src/components/markdown-renderer/markdown-extension/linemarker/linemarker-replacer.tsx b/src/components/markdown-renderer/extensions/linemarker/linemarker-replacer.tsx
similarity index 100%
rename from src/components/markdown-renderer/markdown-extension/linemarker/linemarker-replacer.tsx
rename to src/components/markdown-renderer/extensions/linemarker/linemarker-replacer.tsx
diff --git a/src/components/markdown-renderer/markdown-extension/linemarker/types.d.ts b/src/components/markdown-renderer/extensions/linemarker/types.d.ts
similarity index 75%
rename from src/components/markdown-renderer/markdown-extension/linemarker/types.d.ts
rename to src/components/markdown-renderer/extensions/linemarker/types.d.ts
index 3ef2e8544..44566a65a 100644
--- a/src/components/markdown-renderer/markdown-extension/linemarker/types.d.ts
+++ b/src/components/markdown-renderer/extensions/linemarker/types.d.ts
@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
  *
  * SPDX-License-Identifier: AGPL-3.0-only
  */
diff --git a/src/components/markdown-renderer/markdown-extension/link-replacer/anchor-node-preprocessor.ts b/src/components/markdown-renderer/extensions/link-replacer/anchor-node-preprocessor.ts
similarity index 100%
rename from src/components/markdown-renderer/markdown-extension/link-replacer/anchor-node-preprocessor.ts
rename to src/components/markdown-renderer/extensions/link-replacer/anchor-node-preprocessor.ts
diff --git a/src/components/markdown-renderer/markdown-extension/link-replacer/jump-anchor-replacer.tsx b/src/components/markdown-renderer/extensions/link-replacer/jump-anchor-replacer.tsx
similarity index 100%
rename from src/components/markdown-renderer/markdown-extension/link-replacer/jump-anchor-replacer.tsx
rename to src/components/markdown-renderer/extensions/link-replacer/jump-anchor-replacer.tsx
diff --git a/src/components/markdown-renderer/markdown-extension/link-replacer/jump-anchor.tsx b/src/components/markdown-renderer/extensions/link-replacer/jump-anchor.tsx
similarity index 100%
rename from src/components/markdown-renderer/markdown-extension/link-replacer/jump-anchor.tsx
rename to src/components/markdown-renderer/extensions/link-replacer/jump-anchor.tsx
diff --git a/src/components/markdown-renderer/markdown-extension/link-replacer/link-adjustment-markdown-extension.ts b/src/components/markdown-renderer/extensions/link-replacer/link-adjustment-markdown-extension.ts
similarity index 75%
rename from src/components/markdown-renderer/markdown-extension/link-replacer/link-adjustment-markdown-extension.ts
rename to src/components/markdown-renderer/extensions/link-replacer/link-adjustment-markdown-extension.ts
index ef9956bd1..183895d1f 100644
--- a/src/components/markdown-renderer/markdown-extension/link-replacer/link-adjustment-markdown-extension.ts
+++ b/src/components/markdown-renderer/extensions/link-replacer/link-adjustment-markdown-extension.ts
@@ -1,10 +1,10 @@
 /*
- * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
  *
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
-import { MarkdownExtension } from '../markdown-extension'
+import { MarkdownRendererExtension } from '../base/markdown-renderer-extension'
 import { JumpAnchorReplacer } from './jump-anchor-replacer'
 import type { ComponentReplacer } from '../../replace-components/component-replacer'
 import type { NodeProcessor } from '../../node-preprocessors/node-processor'
@@ -13,7 +13,7 @@ import { AnchorNodePreprocessor } from './anchor-node-preprocessor'
 /**
  * Adds tweaks for anchor tags which are needed for the use in the secured iframe.
  */
-export class LinkAdjustmentMarkdownExtension extends MarkdownExtension {
+export class LinkAdjustmentMarkdownExtension extends MarkdownRendererExtension {
   constructor(private baseUrl: string) {
     super()
   }
diff --git a/src/components/markdown-renderer/markdown-extension/__snapshots__/linkify-fix-markdown-extension.test.tsx.snap b/src/components/markdown-renderer/extensions/linkify-fix/__snapshots__/linkify-fix-markdown-extension.test.tsx.snap
similarity index 100%
rename from src/components/markdown-renderer/markdown-extension/__snapshots__/linkify-fix-markdown-extension.test.tsx.snap
rename to src/components/markdown-renderer/extensions/linkify-fix/__snapshots__/linkify-fix-markdown-extension.test.tsx.snap
diff --git a/src/components/markdown-renderer/markdown-extension/linkify-fix-markdown-extension.test.tsx b/src/components/markdown-renderer/extensions/linkify-fix/linkify-fix-markdown-extension.test.tsx
similarity index 82%
rename from src/components/markdown-renderer/markdown-extension/linkify-fix-markdown-extension.test.tsx
rename to src/components/markdown-renderer/extensions/linkify-fix/linkify-fix-markdown-extension.test.tsx
index 72c45de35..a84cb7e84 100644
--- a/src/components/markdown-renderer/markdown-extension/linkify-fix-markdown-extension.test.tsx
+++ b/src/components/markdown-renderer/extensions/linkify-fix/linkify-fix-markdown-extension.test.tsx
@@ -4,9 +4,9 @@
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
-import { mockI18n } from '../test-utils/mock-i18n'
+import { mockI18n } from '../../test-utils/mock-i18n'
 import { render } from '@testing-library/react'
-import { TestMarkdownRenderer } from '../test-utils/test-markdown-renderer'
+import { TestMarkdownRenderer } from '../../test-utils/test-markdown-renderer'
 import { LinkifyFixMarkdownExtension } from './linkify-fix-markdown-extension'
 
 describe('Linkify markdown extensions', () => {
diff --git a/src/components/markdown-renderer/markdown-extension/linkify-fix-markdown-extension.ts b/src/components/markdown-renderer/extensions/linkify-fix/linkify-fix-markdown-extension.ts
similarity index 80%
rename from src/components/markdown-renderer/markdown-extension/linkify-fix-markdown-extension.ts
rename to src/components/markdown-renderer/extensions/linkify-fix/linkify-fix-markdown-extension.ts
index 1cdeff8c9..2a9fc7e07 100644
--- a/src/components/markdown-renderer/markdown-extension/linkify-fix-markdown-extension.ts
+++ b/src/components/markdown-renderer/extensions/linkify-fix/linkify-fix-markdown-extension.ts
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
-import { MarkdownExtension } from './markdown-extension'
+import { MarkdownRendererExtension } from '../base/markdown-renderer-extension'
 import linkify from 'markdown-it/lib/rules_core/linkify'
 import type MarkdownIt from 'markdown-it'
 import tlds from 'tlds'
@@ -12,7 +12,7 @@ import tlds from 'tlds'
 /**
  * A markdown extension that detects plain text URLs and converts them into links.
  */
-export class LinkifyFixMarkdownExtension extends MarkdownExtension {
+export class LinkifyFixMarkdownExtension extends MarkdownRendererExtension {
   public configureMarkdownItPost(markdownIt: MarkdownIt): void {
     markdownIt.linkify.tlds(tlds)
     markdownIt.core.ruler.push('linkify', (state) => {
diff --git a/src/components/markdown-renderer/markdown-extension/reveal/process-reveal-comment-nodes.ts b/src/components/markdown-renderer/extensions/reveal/process-reveal-comment-nodes.ts
similarity index 100%
rename from src/components/markdown-renderer/markdown-extension/reveal/process-reveal-comment-nodes.ts
rename to src/components/markdown-renderer/extensions/reveal/process-reveal-comment-nodes.ts
diff --git a/src/components/markdown-renderer/markdown-extension/reveal/reveal-markdown-extension.ts b/src/components/markdown-renderer/extensions/reveal/reveal-markdown-extension.ts
similarity index 77%
rename from src/components/markdown-renderer/markdown-extension/reveal/reveal-markdown-extension.ts
rename to src/components/markdown-renderer/extensions/reveal/reveal-markdown-extension.ts
index 9c3e525fd..5fc4ee53a 100644
--- a/src/components/markdown-renderer/markdown-extension/reveal/reveal-markdown-extension.ts
+++ b/src/components/markdown-renderer/extensions/reveal/reveal-markdown-extension.ts
@@ -1,10 +1,10 @@
 /*
- * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
  *
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
-import { MarkdownExtension } from '../markdown-extension'
+import { MarkdownRendererExtension } from '../base/markdown-renderer-extension'
 import type MarkdownIt from 'markdown-it'
 import { addSlideSectionsMarkdownItPlugin } from './reveal-sections'
 import { RevealCommentCommandNodePreprocessor } from './process-reveal-comment-nodes'
@@ -14,7 +14,7 @@ import type { NodeProcessor } from '../../node-preprocessors/node-processor'
  * Adds support for reveal.js to the markdown rendering.
  * This includes the generation of sections and the manipulation of elements using reveal comments.
  */
-export class RevealMarkdownExtension extends MarkdownExtension {
+export class RevealMarkdownExtension extends MarkdownRendererExtension {
   public configureMarkdownIt(markdownIt: MarkdownIt): void {
     addSlideSectionsMarkdownItPlugin(markdownIt)
   }
diff --git a/src/components/markdown-renderer/markdown-extension/reveal/reveal-sections.ts b/src/components/markdown-renderer/extensions/reveal/reveal-sections.ts
similarity index 97%
rename from src/components/markdown-renderer/markdown-extension/reveal/reveal-sections.ts
rename to src/components/markdown-renderer/extensions/reveal/reveal-sections.ts
index 1a0c5069e..a4f23e5e8 100644
--- a/src/components/markdown-renderer/markdown-extension/reveal/reveal-sections.ts
+++ b/src/components/markdown-renderer/extensions/reveal/reveal-sections.ts
@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
  *
  * SPDX-License-Identifier: AGPL-3.0-only
  */
diff --git a/src/components/markdown-renderer/markdown-extension/sanitizer/dom-purifier-node-preprocessor.ts b/src/components/markdown-renderer/extensions/sanitizer/dom-purifier-node-preprocessor.ts
similarity index 100%
rename from src/components/markdown-renderer/markdown-extension/sanitizer/dom-purifier-node-preprocessor.ts
rename to src/components/markdown-renderer/extensions/sanitizer/dom-purifier-node-preprocessor.ts
diff --git a/src/components/markdown-renderer/markdown-extension/sanitizer/sanitizer-markdown-extension.ts b/src/components/markdown-renderer/extensions/sanitizer/sanitizer-markdown-extension.ts
similarity index 69%
rename from src/components/markdown-renderer/markdown-extension/sanitizer/sanitizer-markdown-extension.ts
rename to src/components/markdown-renderer/extensions/sanitizer/sanitizer-markdown-extension.ts
index 545bdbc0e..d66b8f31c 100644
--- a/src/components/markdown-renderer/markdown-extension/sanitizer/sanitizer-markdown-extension.ts
+++ b/src/components/markdown-renderer/extensions/sanitizer/sanitizer-markdown-extension.ts
@@ -1,17 +1,17 @@
 /*
- * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
  *
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
-import { MarkdownExtension } from '../markdown-extension'
 import { SanitizerNodePreprocessor } from './dom-purifier-node-preprocessor'
 import type { NodeProcessor } from '../../node-preprocessors/node-processor'
+import { MarkdownRendererExtension } from '../base/markdown-renderer-extension'
 
 /**
  * Adds support for html sanitizing using dompurify to the markdown rendering.
  */
-export class SanitizerMarkdownExtension extends MarkdownExtension {
+export class SanitizerMarkdownExtension extends MarkdownRendererExtension {
   constructor(private tagNameWhiteList: string[]) {
     super()
   }
diff --git a/src/components/markdown-renderer/markdown-extension/table-of-contents-markdown-extension.ts b/src/components/markdown-renderer/extensions/table-of-contents-markdown-extension.ts
similarity index 59%
rename from src/components/markdown-renderer/markdown-extension/table-of-contents-markdown-extension.ts
rename to src/components/markdown-renderer/extensions/table-of-contents-markdown-extension.ts
index 62892d9fc..04b7d83e3 100644
--- a/src/components/markdown-renderer/markdown-extension/table-of-contents-markdown-extension.ts
+++ b/src/components/markdown-renderer/extensions/table-of-contents-markdown-extension.ts
@@ -4,29 +4,31 @@
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
-import { MarkdownExtension } from './markdown-extension'
 import type MarkdownIt from 'markdown-it'
 import type { TocAst } from 'markdown-it-toc-done-right'
 import toc from 'markdown-it-toc-done-right'
 import { tocSlugify } from '../../editor-page/table-of-contents/toc-slugify'
+import { MarkdownRendererExtension } from './base/markdown-renderer-extension'
+import equal from 'fast-deep-equal'
+
 /**
  * Adds table of content to the markdown rendering.
  */
-export class TableOfContentsMarkdownExtension extends MarkdownExtension {
-  constructor(private onTocChange?: (ast: TocAst) => void) {
-    super()
-  }
+export class TableOfContentsMarkdownExtension extends MarkdownRendererExtension {
+  public static readonly EVENT_NAME = 'TocChange'
+  private lastAst: TocAst | undefined = undefined
 
   public configureMarkdownIt(markdownIt: MarkdownIt): void {
-    if (!this.onTocChange) {
-      return
-    }
     toc(markdownIt, {
       placeholder: '(\\[TOC\\]|\\[toc\\])',
       listType: 'ul',
       level: [1, 2, 3],
       callback: (code: string, ast: TocAst): void => {
-        this.onTocChange?.(ast)
+        if (equal(ast, this.lastAst)) {
+          return
+        }
+        this.lastAst = ast
+        this.eventEmitter?.emit(TableOfContentsMarkdownExtension.EVENT_NAME, ast)
       },
       slugify: tocSlugify
     })
diff --git a/src/components/markdown-renderer/markdown-extension/upload-indicating-image-frame/upload-indicating-frame.tsx b/src/components/markdown-renderer/extensions/upload-indicating-image-frame/upload-indicating-frame.tsx
similarity index 94%
rename from src/components/markdown-renderer/markdown-extension/upload-indicating-image-frame/upload-indicating-frame.tsx
rename to src/components/markdown-renderer/extensions/upload-indicating-image-frame/upload-indicating-frame.tsx
index 72a99de57..90454cb98 100644
--- a/src/components/markdown-renderer/markdown-extension/upload-indicating-image-frame/upload-indicating-frame.tsx
+++ b/src/components/markdown-renderer/extensions/upload-indicating-image-frame/upload-indicating-frame.tsx
@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
  *
  * SPDX-License-Identifier: AGPL-3.0-only
  */
diff --git a/src/components/markdown-renderer/markdown-extension/upload-indicating-image-frame/upload-indicating-image-frame-markdown-extension.ts b/src/components/markdown-renderer/extensions/upload-indicating-image-frame/upload-indicating-image-frame-markdown-extension.ts
similarity index 75%
rename from src/components/markdown-renderer/markdown-extension/upload-indicating-image-frame/upload-indicating-image-frame-markdown-extension.ts
rename to src/components/markdown-renderer/extensions/upload-indicating-image-frame/upload-indicating-image-frame-markdown-extension.ts
index c24c4bcc7..ff6d2efb0 100644
--- a/src/components/markdown-renderer/markdown-extension/upload-indicating-image-frame/upload-indicating-image-frame-markdown-extension.ts
+++ b/src/components/markdown-renderer/extensions/upload-indicating-image-frame/upload-indicating-image-frame-markdown-extension.ts
@@ -1,17 +1,17 @@
 /*
- * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
  *
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
-import { MarkdownExtension } from '../markdown-extension'
+import { MarkdownRendererExtension } from '../base/markdown-renderer-extension'
 import type { ComponentReplacer } from '../../replace-components/component-replacer'
 import { UploadIndicatingImageFrameReplacer } from './upload-indicating-image-frame-replacer'
 
 /**
  * A markdown extension that shows {@link UploadIndicatingFrame} for images that are getting uploaded.
  */
-export class UploadIndicatingImageFrameMarkdownExtension extends MarkdownExtension {
+export class UploadIndicatingImageFrameMarkdownExtension extends MarkdownRendererExtension {
   buildReplacers(): ComponentReplacer[] {
     return [new UploadIndicatingImageFrameReplacer()]
   }
diff --git a/src/components/markdown-renderer/markdown-extension/upload-indicating-image-frame/upload-indicating-image-frame-replacer.tsx b/src/components/markdown-renderer/extensions/upload-indicating-image-frame/upload-indicating-image-frame-replacer.tsx
similarity index 100%
rename from src/components/markdown-renderer/markdown-extension/upload-indicating-image-frame/upload-indicating-image-frame-replacer.tsx
rename to src/components/markdown-renderer/extensions/upload-indicating-image-frame/upload-indicating-image-frame-replacer.tsx
diff --git a/src/components/markdown-renderer/hooks/use-combined-node-preprocessor.ts b/src/components/markdown-renderer/hooks/use-combined-node-preprocessor.ts
new file mode 100644
index 000000000..ebfb8ebac
--- /dev/null
+++ b/src/components/markdown-renderer/hooks/use-combined-node-preprocessor.ts
@@ -0,0 +1,25 @@
+/*
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import { useMemo } from 'react'
+import type { Document } from 'domhandler'
+import type { MarkdownRendererExtension } from '../extensions/base/markdown-renderer-extension'
+
+/**
+ * Creates a function that applies the node preprocessors of every given {@link MarkdownRendererExtension} to a {@link Document}.
+ *
+ * @param extensions The extensions who provide node processors
+ * @return The created apply function
+ */
+export const useCombinedNodePreprocessor = (extensions: MarkdownRendererExtension[]): ((nodes: Document) => Document) =>
+  useMemo(() => {
+    return extensions
+      .flatMap((extension) => extension.buildNodeProcessors())
+      .reduce(
+        (state, processor) => (document: Document) => state(processor.process(document)),
+        (document: Document) => document
+      )
+  }, [extensions])
diff --git a/src/components/markdown-renderer/hooks/use-configured-markdown-it.ts b/src/components/markdown-renderer/hooks/use-configured-markdown-it.ts
new file mode 100644
index 000000000..ce2f66d43
--- /dev/null
+++ b/src/components/markdown-renderer/hooks/use-configured-markdown-it.ts
@@ -0,0 +1,35 @@
+/*
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import { useMemo } from 'react'
+import MarkdownIt from 'markdown-it/lib'
+import type { MarkdownRendererExtension } from '../extensions/base/markdown-renderer-extension'
+
+/**
+ * Creates a new {@link MarkdownIt markdown-it instance} and configures it using the given {@link MarkdownRendererExtension markdown renderer extensions}.
+ *
+ * @param extensions The extensions that configure the new markdown-it instance
+ * @param allowHtml Defines if html in markdown is allowed
+ * @param newlinesAreBreaks Defines if new lines should be treated as line breaks or paragraphs
+ * @return the created markdown-it instance
+ */
+export const useConfiguredMarkdownIt = (
+  extensions: MarkdownRendererExtension[],
+  allowHtml: boolean,
+  newlinesAreBreaks: boolean
+): MarkdownIt => {
+  return useMemo(() => {
+    const newMarkdownIt = new MarkdownIt('default', {
+      html: allowHtml,
+      breaks: newlinesAreBreaks,
+      langPrefix: '',
+      typographer: true
+    })
+    extensions.forEach((extension) => newMarkdownIt.use((markdownIt) => extension.configureMarkdownIt(markdownIt)))
+    extensions.forEach((extension) => newMarkdownIt.use((markdownIt) => extension.configureMarkdownItPost(markdownIt)))
+    return newMarkdownIt
+  }, [allowHtml, extensions, newlinesAreBreaks])
+}
diff --git a/src/components/markdown-renderer/hooks/use-convert-markdown-to-react-dom.ts b/src/components/markdown-renderer/hooks/use-convert-markdown-to-react-dom.ts
deleted file mode 100644
index d829ff861..000000000
--- a/src/components/markdown-renderer/hooks/use-convert-markdown-to-react-dom.ts
+++ /dev/null
@@ -1,68 +0,0 @@
-/*
- * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
- *
- * SPDX-License-Identifier: AGPL-3.0-only
- */
-
-import MarkdownIt from 'markdown-it/lib'
-import { useMemo } from 'react'
-import type { ValidReactDomElement } from '../replace-components/component-replacer'
-import convertHtmlToReact from '@hedgedoc/html-to-react'
-import { NodeToReactTransformer } from '../utils/node-to-react-transformer'
-import { LineIdMapper } from '../utils/line-id-mapper'
-import type { MarkdownExtension } from '../markdown-extension/markdown-extension'
-import { MarkdownExtensionCollection } from '../markdown-extension/markdown-extension-collection'
-
-/**
- * Renders Markdown-Code into react elements.
- *
- * @param markdownContentLines The markdown code lines that should be rendered
- * @param additionalMarkdownExtensions A list of {@link MarkdownExtension markdown extensions} that should be used
- * @param newlinesAreBreaks Defines if the alternative break mode of markdown it should be used
- * @param allowHtml Defines if html is allowed in markdown
- * @return The React DOM that represents the rendered markdown code
- */
-export const useConvertMarkdownToReactDom = (
-  markdownContentLines: string[],
-  additionalMarkdownExtensions: MarkdownExtension[],
-  newlinesAreBreaks = true,
-  allowHtml = true
-): ValidReactDomElement[] => {
-  const lineNumberMapper = useMemo(() => new LineIdMapper(), [])
-  const htmlToReactTransformer = useMemo(() => new NodeToReactTransformer(), [])
-  const markdownExtensions = useMemo(
-    () => new MarkdownExtensionCollection(additionalMarkdownExtensions),
-    [additionalMarkdownExtensions]
-  )
-
-  const markdownIt = useMemo(() => {
-    const newMarkdownIt = new MarkdownIt('default', {
-      html: allowHtml,
-      breaks: newlinesAreBreaks,
-      langPrefix: '',
-      typographer: true
-    })
-    markdownExtensions.configureMarkdownIt(newMarkdownIt)
-    return newMarkdownIt
-  }, [allowHtml, markdownExtensions, newlinesAreBreaks])
-
-  useMemo(() => {
-    htmlToReactTransformer.setReplacers(markdownExtensions.buildReplacers())
-  }, [htmlToReactTransformer, markdownExtensions])
-
-  useMemo(() => {
-    htmlToReactTransformer.setLineIds(lineNumberMapper.updateLineMapping(markdownContentLines))
-  }, [htmlToReactTransformer, lineNumberMapper, markdownContentLines])
-
-  const nodePreProcessor = useMemo(() => markdownExtensions.buildFlatNodeProcessor(), [markdownExtensions])
-
-  return useMemo(() => {
-    const html = markdownIt.render(markdownContentLines.join('\n'))
-    htmlToReactTransformer.resetReplacers()
-
-    return convertHtmlToReact(html, {
-      transform: (node, index) => htmlToReactTransformer.translateNodeToReactElement(node, index),
-      preprocessNodes: (document) => nodePreProcessor(document)
-    })
-  }, [htmlToReactTransformer, markdownContentLines, markdownIt, nodePreProcessor])
-}
diff --git a/src/components/markdown-renderer/hooks/use-convert-markdown-to-react-dom.tsx b/src/components/markdown-renderer/hooks/use-convert-markdown-to-react-dom.tsx
new file mode 100644
index 000000000..4522c29f0
--- /dev/null
+++ b/src/components/markdown-renderer/hooks/use-convert-markdown-to-react-dom.tsx
@@ -0,0 +1,63 @@
+/*
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import React, { Fragment, useMemo } from 'react'
+import type { ValidReactDomElement } from '../replace-components/component-replacer'
+import convertHtmlToReact from '@hedgedoc/html-to-react'
+import { NodeToReactTransformer } from '../utils/node-to-react-transformer'
+import { LineIdMapper } from '../utils/line-id-mapper'
+import type { MarkdownRendererExtension } from '../extensions/base/markdown-renderer-extension'
+import { SanitizerMarkdownExtension } from '../extensions/sanitizer/sanitizer-markdown-extension'
+import { useCombinedNodePreprocessor } from './use-combined-node-preprocessor'
+import { useConfiguredMarkdownIt } from './use-configured-markdown-it'
+
+/**
+ * Renders Markdown-Code into react elements.
+ *
+ * @param markdownContentLines The Markdown code lines that should be rendered
+ * @param additionalMarkdownExtensions A list of {@link MarkdownRendererExtension markdown extensions} that should be used
+ * @param newlinesAreBreaks Defines if the alternative break mode of markdown it should be used
+ * @param allowHtml Defines if html is allowed in markdown
+ * @return The React DOM that represents the rendered Markdown code
+ */
+export const useConvertMarkdownToReactDom = (
+  markdownContentLines: string[],
+  additionalMarkdownExtensions: MarkdownRendererExtension[],
+  newlinesAreBreaks = true,
+  allowHtml = true
+): ValidReactDomElement => {
+  const lineNumberMapper = useMemo(() => new LineIdMapper(), [])
+  const htmlToReactTransformer = useMemo(() => new NodeToReactTransformer(), [])
+  const markdownExtensions = useMemo(() => {
+    const tagWhiteLists = additionalMarkdownExtensions.flatMap((extension) => extension.buildTagNameAllowList())
+    return [...additionalMarkdownExtensions, new SanitizerMarkdownExtension(tagWhiteLists)]
+  }, [additionalMarkdownExtensions])
+
+  useMemo(() => {
+    htmlToReactTransformer.setReplacers(markdownExtensions.flatMap((extension) => extension.buildReplacers()))
+  }, [htmlToReactTransformer, markdownExtensions])
+
+  useMemo(() => {
+    htmlToReactTransformer.setLineIds(lineNumberMapper.updateLineMapping(markdownContentLines))
+  }, [htmlToReactTransformer, lineNumberMapper, markdownContentLines])
+
+  const nodePreProcessor = useCombinedNodePreprocessor(markdownExtensions)
+  const markdownIt = useConfiguredMarkdownIt(markdownExtensions, allowHtml, newlinesAreBreaks)
+
+  return useMemo(() => {
+    const html = markdownIt.render(markdownContentLines.join('\n'))
+    htmlToReactTransformer.resetReplacers()
+
+    return (
+      <Fragment key={'root'}>
+        {convertHtmlToReact(html, {
+          transform: (node, index) => htmlToReactTransformer.translateNodeToReactElement(node, index),
+          preprocessNodes: (document) => nodePreProcessor(document)
+        })}
+      </Fragment>
+    )
+  }, [htmlToReactTransformer, markdownContentLines, markdownIt, nodePreProcessor])
+}
diff --git a/src/components/markdown-renderer/hooks/use-extension-event-emitter.tsx b/src/components/markdown-renderer/hooks/use-extension-event-emitter.tsx
new file mode 100644
index 000000000..cdf002505
--- /dev/null
+++ b/src/components/markdown-renderer/hooks/use-extension-event-emitter.tsx
@@ -0,0 +1,51 @@
+/*
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import type { PropsWithChildren } from 'react'
+import React, { createContext, useContext, useEffect, useMemo } from 'react'
+import EventEmitter2 from 'eventemitter2'
+
+export const eventEmitterContext = createContext<EventEmitter2 | undefined>(undefined)
+
+/**
+ * Provides the {@link EventEmitter2 event emitter} from the current {@link eventEmitterContext context}.
+ */
+export const useExtensionEventEmitter = () => {
+  return useContext(eventEmitterContext)
+}
+
+/**
+ * Creates a new {@link EventEmitter2 event emitter} and provides it as {@link eventEmitterContext context}.
+ *
+ * @param children The elements that should receive the context value
+ */
+export const ExtensionEventEmitterProvider: React.FC<PropsWithChildren> = ({ children }) => {
+  const eventEmitter = useMemo(() => new EventEmitter2(), [])
+  return <eventEmitterContext.Provider value={eventEmitter}>{children}</eventEmitterContext.Provider>
+}
+
+/**
+ * Registers a handler callback on the current {@link EventEmitter2 event emitter} that is provided in the {@link eventEmitterContext context}.
+ *
+ * @param eventName The name of the event which should be subscribed
+ * @param handler The callback that should be executed. If undefined the event will be unsubscribed.
+ */
+export const useExtensionEventEmitterHandler = <T,>(
+  eventName: string,
+  handler: ((values: T) => void) | undefined
+): void => {
+  const eventEmitter = useExtensionEventEmitter()
+
+  useEffect(() => {
+    if (!eventEmitter || !handler) {
+      return
+    }
+    eventEmitter.on(eventName, handler)
+    return () => {
+      eventEmitter.off(eventName, handler)
+    }
+  }, [eventEmitter, eventName, handler])
+}
diff --git a/src/components/markdown-renderer/hooks/use-markdown-extensions.ts b/src/components/markdown-renderer/hooks/use-markdown-extensions.ts
index 377d113bc..97db98a3c 100644
--- a/src/components/markdown-renderer/hooks/use-markdown-extensions.ts
+++ b/src/components/markdown-renderer/hooks/use-markdown-extensions.ts
@@ -5,98 +5,59 @@
  */
 
 import type { MutableRefObject } from 'react'
-import { useMemo, useRef } from 'react'
-import { TableOfContentsMarkdownExtension } from '../markdown-extension/table-of-contents-markdown-extension'
-import { VegaLiteMarkdownExtension } from '../markdown-extension/vega-lite/vega-lite-markdown-extension'
-import { LinemarkerMarkdownExtension } from '../markdown-extension/linemarker/linemarker-markdown-extension'
-import { GistMarkdownExtension } from '../markdown-extension/gist/gist-markdown-extension'
-import { YoutubeMarkdownExtension } from '../markdown-extension/youtube/youtube-markdown-extension'
-import { VimeoMarkdownExtension } from '../markdown-extension/vimeo/vimeo-markdown-extension'
-import { ProxyImageMarkdownExtension } from '../markdown-extension/image/proxy-image-markdown-extension'
-import { CsvTableMarkdownExtension } from '../markdown-extension/csv/csv-table-markdown-extension'
-import { AbcjsMarkdownExtension } from '../markdown-extension/abcjs/abcjs-markdown-extension'
-import { SequenceDiagramMarkdownExtension } from '../markdown-extension/sequence-diagram/sequence-diagram-markdown-extension'
-import { FlowchartMarkdownExtension } from '../markdown-extension/flowchart/flowchart-markdown-extension'
-import { MermaidMarkdownExtension } from '../markdown-extension/mermaid/mermaid-markdown-extension'
-import { GraphvizMarkdownExtension } from '../markdown-extension/graphviz/graphviz-markdown-extension'
-import { BlockquoteExtraTagMarkdownExtension } from '../markdown-extension/blockquote/blockquote-extra-tag-markdown-extension'
-import { LinkAdjustmentMarkdownExtension } from '../markdown-extension/link-replacer/link-adjustment-markdown-extension'
-import { KatexMarkdownExtension } from '../markdown-extension/katex/katex-markdown-extension'
-import { TaskListMarkdownExtension } from '../markdown-extension/task-list/task-list-markdown-extension'
-import { PlantumlMarkdownExtension } from '../markdown-extension/plantuml/plantuml-markdown-extension'
-import { LegacyShortcodesMarkdownExtension } from '../markdown-extension/legacy-short-codes/legacy-shortcodes-markdown-extension'
-import { EmojiMarkdownExtension } from '../markdown-extension/emoji/emoji-markdown-extension'
-import { GenericSyntaxMarkdownExtension } from '../markdown-extension/generic-syntax-markdown-extension'
-import { AlertMarkdownExtension } from '../markdown-extension/alert-markdown-extension'
-import { SpoilerMarkdownExtension } from '../markdown-extension/spoiler-markdown-extension'
-import { LinkifyFixMarkdownExtension } from '../markdown-extension/linkify-fix-markdown-extension'
-import { HighlightedCodeMarkdownExtension } from '../markdown-extension/highlighted-fence/highlighted-code-markdown-extension'
-import { DebuggerMarkdownExtension } from '../markdown-extension/debugger-markdown-extension'
-import type { LineMarkers } from '../markdown-extension/linemarker/add-line-marker-markdown-it-plugin'
-import type { ImageClickHandler } from '../markdown-extension/image/proxy-image-replacer'
-import type { TocAst } from 'markdown-it-toc-done-right'
-import type { MarkdownExtension } from '../markdown-extension/markdown-extension'
-import { IframeCapsuleMarkdownExtension } from '../markdown-extension/iframe-capsule/iframe-capsule-markdown-extension'
-import { ImagePlaceholderMarkdownExtension } from '../markdown-extension/image-placeholder/image-placeholder-markdown-extension'
-import { UploadIndicatingImageFrameMarkdownExtension } from '../markdown-extension/upload-indicating-image-frame/upload-indicating-image-frame-markdown-extension'
-import { useOnRefChange } from './use-on-ref-change'
+import { useMemo } from 'react'
+import { GenericSyntaxMarkdownExtension } from '../extensions/generic-syntax-markdown-extension'
+import type { LineMarkers } from '../extensions/linemarker/add-line-marker-markdown-it-plugin'
+import { DebuggerMarkdownExtension } from '../extensions/debugger-markdown-extension'
+import { UploadIndicatingImageFrameMarkdownExtension } from '../extensions/upload-indicating-image-frame/upload-indicating-image-frame-markdown-extension'
+import { IframeCapsuleMarkdownExtension } from '../extensions/iframe-capsule/iframe-capsule-markdown-extension'
+import { LinkifyFixMarkdownExtension } from '../extensions/linkify-fix/linkify-fix-markdown-extension'
+import { LinkAdjustmentMarkdownExtension } from '../extensions/link-replacer/link-adjustment-markdown-extension'
+import { EmojiMarkdownExtension } from '../extensions/emoji/emoji-markdown-extension'
+import { LinemarkerMarkdownExtension } from '../extensions/linemarker/linemarker-markdown-extension'
+import { TableOfContentsMarkdownExtension } from '../extensions/table-of-contents-markdown-extension'
+import { ImagePlaceholderMarkdownExtension } from '../extensions/image-placeholder/image-placeholder-markdown-extension'
+import type { MarkdownRendererExtension } from '../extensions/base/markdown-renderer-extension'
+import { useExtensionEventEmitter } from './use-extension-event-emitter'
+import { optionalAppExtensions } from '../../../extensions/extra-integrations/optional-app-extensions'
+import { ProxyImageMarkdownExtension } from '../extensions/image/proxy-image-markdown-extension'
+
+const optionalMarkdownRendererExtensions = optionalAppExtensions.flatMap((value) =>
+  value.buildMarkdownRendererExtensions()
+)
 
 /**
- * Provides a list of {@link MarkdownExtension markdown extensions} that is a combination of the common extensions and the given additional.
+ * Provides a list of {@link MarkdownRendererExtension markdown extensions} that is a combination of the common extensions and the given additional.
  *
  * @param baseUrl The base url for the {@link LinkAdjustmentMarkdownExtension}
  * @param currentLineMarkers A {@link MutableRefObject reference} to {@link LineMarkers} for the {@link LinemarkerMarkdownExtension}
  * @param additionalExtensions The additional extensions that should be included in the list
- * @param onTaskCheckedChange The checkbox click callback for the {@link TaskListMarkdownExtension}
- * @param onImageClick The image click callback for the {@link ProxyImageMarkdownExtension}
- * @param onTocChange The toc-changed callback for the {@link TableOfContentsMarkdownExtension}
  * @return The created list of markdown extensions
  */
 export const useMarkdownExtensions = (
   baseUrl: string,
   currentLineMarkers: MutableRefObject<LineMarkers[] | undefined> | undefined,
-  additionalExtensions: MarkdownExtension[],
-  onTaskCheckedChange?: (lineInMarkdown: number, checked: boolean) => void,
-  onImageClick?: ImageClickHandler,
-  onTocChange?: (ast?: TocAst) => void
-): MarkdownExtension[] => {
-  const toc = useRef<TocAst | undefined>(undefined)
-  useOnRefChange(toc, onTocChange)
-
+  additionalExtensions: MarkdownRendererExtension[]
+): MarkdownRendererExtension[] => {
+  const extensionEventEmitter = useExtensionEventEmitter()
+  //replace with global list
   return useMemo(() => {
     return [
-      new TableOfContentsMarkdownExtension((ast?: TocAst) => (toc.current = ast)),
+      ...optionalMarkdownRendererExtensions,
       ...additionalExtensions,
-      new VegaLiteMarkdownExtension(),
+      new TableOfContentsMarkdownExtension(extensionEventEmitter),
       new LinemarkerMarkdownExtension(
         currentLineMarkers ? (lineMarkers) => (currentLineMarkers.current = lineMarkers) : undefined
       ),
       new IframeCapsuleMarkdownExtension(),
       new ImagePlaceholderMarkdownExtension(),
       new UploadIndicatingImageFrameMarkdownExtension(),
-      new GistMarkdownExtension(),
-      new YoutubeMarkdownExtension(),
-      new VimeoMarkdownExtension(),
-      new ProxyImageMarkdownExtension(onImageClick),
-      new CsvTableMarkdownExtension(),
-      new AbcjsMarkdownExtension(),
-      new SequenceDiagramMarkdownExtension(),
-      new FlowchartMarkdownExtension(),
-      new MermaidMarkdownExtension(),
-      new GraphvizMarkdownExtension(),
-      new BlockquoteExtraTagMarkdownExtension(),
       new LinkAdjustmentMarkdownExtension(baseUrl),
-      new KatexMarkdownExtension(),
-      new TaskListMarkdownExtension(onTaskCheckedChange),
-      new PlantumlMarkdownExtension(),
-      new LegacyShortcodesMarkdownExtension(),
       new EmojiMarkdownExtension(),
       new GenericSyntaxMarkdownExtension(),
-      new AlertMarkdownExtension(),
-      new SpoilerMarkdownExtension(),
       new LinkifyFixMarkdownExtension(),
-      new HighlightedCodeMarkdownExtension(),
-      new DebuggerMarkdownExtension()
+      new DebuggerMarkdownExtension(),
+      new ProxyImageMarkdownExtension()
     ]
-  }, [additionalExtensions, baseUrl, currentLineMarkers, onImageClick, onTaskCheckedChange])
+  }, [additionalExtensions, baseUrl, currentLineMarkers, extensionEventEmitter])
 }
diff --git a/src/components/markdown-renderer/markdown-extension/abcjs/abcjs-markdown-extension.ts b/src/components/markdown-renderer/markdown-extension/abcjs/abcjs-markdown-extension.ts
deleted file mode 100644
index 1ba1b56e0..000000000
--- a/src/components/markdown-renderer/markdown-extension/abcjs/abcjs-markdown-extension.ts
+++ /dev/null
@@ -1,19 +0,0 @@
-/*
- * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
- *
- * SPDX-License-Identifier: AGPL-3.0-only
- */
-
-import { CodeBlockComponentReplacer } from '../../replace-components/code-block-component-replacer'
-import { AbcFrame } from './abc-frame'
-import type { ComponentReplacer } from '../../replace-components/component-replacer'
-import { CodeBlockMarkdownExtension } from '../code-block-markdown-extension/code-block-markdown-extension'
-
-/**
- * Adds support for abc.js to the markdown rendering using code fences with "abc" as language.
- */
-export class AbcjsMarkdownExtension extends CodeBlockMarkdownExtension {
-  public buildReplacers(): ComponentReplacer[] {
-    return [new CodeBlockComponentReplacer(AbcFrame, 'abc')]
-  }
-}
diff --git a/src/components/markdown-renderer/markdown-extension/code-block-markdown-extension/code-block-markdown-extension.ts b/src/components/markdown-renderer/markdown-extension/code-block-markdown-extension/code-block-markdown-extension.ts
deleted file mode 100644
index 2e26fc3af..000000000
--- a/src/components/markdown-renderer/markdown-extension/code-block-markdown-extension/code-block-markdown-extension.ts
+++ /dev/null
@@ -1,18 +0,0 @@
-/*
- * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
- *
- * SPDX-License-Identifier: AGPL-3.0-only
- */
-
-import type MarkdownIt from 'markdown-it'
-import { codeBlockMarkdownPlugin } from './code-block-markdown-plugin'
-import { MarkdownExtension } from '../markdown-extension'
-
-/**
- * A {@link MarkdownExtension markdown extension} that is used for code fence replacements.
- */
-export abstract class CodeBlockMarkdownExtension extends MarkdownExtension {
-  public configureMarkdownIt(markdownIt: MarkdownIt): void {
-    codeBlockMarkdownPlugin(markdownIt)
-  }
-}
diff --git a/src/components/markdown-renderer/markdown-extension/csv/csv-table-markdown-extension.ts b/src/components/markdown-renderer/markdown-extension/csv/csv-table-markdown-extension.ts
deleted file mode 100644
index 2c43a12d2..000000000
--- a/src/components/markdown-renderer/markdown-extension/csv/csv-table-markdown-extension.ts
+++ /dev/null
@@ -1,18 +0,0 @@
-/*
- * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
- *
- * SPDX-License-Identifier: AGPL-3.0-only
- */
-
-import { MarkdownExtension } from '../markdown-extension'
-import { CsvReplacer } from './csv-replacer'
-import type { ComponentReplacer } from '../../replace-components/component-replacer'
-
-/**
- * Adds support for csv tables to the markdown rendering using code fences with "csv" as language.
- */
-export class CsvTableMarkdownExtension extends MarkdownExtension {
-  public buildReplacers(): ComponentReplacer[] {
-    return [new CsvReplacer()]
-  }
-}
diff --git a/src/components/markdown-renderer/markdown-extension/flowchart/flowchart-markdown-extension.ts b/src/components/markdown-renderer/markdown-extension/flowchart/flowchart-markdown-extension.ts
deleted file mode 100644
index 62ae03b6a..000000000
--- a/src/components/markdown-renderer/markdown-extension/flowchart/flowchart-markdown-extension.ts
+++ /dev/null
@@ -1,19 +0,0 @@
-/*
- * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
- *
- * SPDX-License-Identifier: AGPL-3.0-only
- */
-
-import { CodeBlockComponentReplacer } from '../../replace-components/code-block-component-replacer'
-import type { ComponentReplacer } from '../../replace-components/component-replacer'
-import { FlowChart } from './flowchart'
-import { CodeBlockMarkdownExtension } from '../code-block-markdown-extension/code-block-markdown-extension'
-
-/**
- * Adds support for flow charts to the markdown rendering using code fences with "flow" as language.
- */
-export class FlowchartMarkdownExtension extends CodeBlockMarkdownExtension {
-  public buildReplacers(): ComponentReplacer[] {
-    return [new CodeBlockComponentReplacer(FlowChart, 'flow')]
-  }
-}
diff --git a/src/components/markdown-renderer/markdown-extension/graphviz/graphviz-markdown-extension.ts b/src/components/markdown-renderer/markdown-extension/graphviz/graphviz-markdown-extension.ts
deleted file mode 100644
index dc9d62a78..000000000
--- a/src/components/markdown-renderer/markdown-extension/graphviz/graphviz-markdown-extension.ts
+++ /dev/null
@@ -1,19 +0,0 @@
-/*
- * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
- *
- * SPDX-License-Identifier: AGPL-3.0-only
- */
-
-import { CodeBlockComponentReplacer } from '../../replace-components/code-block-component-replacer'
-import type { ComponentReplacer } from '../../replace-components/component-replacer'
-import { GraphvizFrame } from './graphviz-frame'
-import { CodeBlockMarkdownExtension } from '../code-block-markdown-extension/code-block-markdown-extension'
-
-/**
- * Adds support for graphviz to the markdown rendering using code fences with "graphviz" as language.
- */
-export class GraphvizMarkdownExtension extends CodeBlockMarkdownExtension {
-  public buildReplacers(): ComponentReplacer[] {
-    return [new CodeBlockComponentReplacer(GraphvizFrame, 'graphviz')]
-  }
-}
diff --git a/src/components/markdown-renderer/markdown-extension/highlighted-fence/highlighted-code-markdown-extension.ts b/src/components/markdown-renderer/markdown-extension/highlighted-fence/highlighted-code-markdown-extension.ts
deleted file mode 100644
index 911fbef98..000000000
--- a/src/components/markdown-renderer/markdown-extension/highlighted-fence/highlighted-code-markdown-extension.ts
+++ /dev/null
@@ -1,19 +0,0 @@
-/*
- * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
- *
- * SPDX-License-Identifier: AGPL-3.0-only
- */
-
-import { HighlightedCodeReplacer } from './highlighted-code-replacer'
-import type { ComponentReplacer } from '../../replace-components/component-replacer'
-import { CodeBlockMarkdownExtension } from '../code-block-markdown-extension/code-block-markdown-extension'
-
-/**
- * Adds support code highlighting to the markdown rendering.
- * Every code fence that is not replaced by another replacer is highlighted using highlight-js.
- */
-export class HighlightedCodeMarkdownExtension extends CodeBlockMarkdownExtension {
-  public buildReplacers(): ComponentReplacer[] {
-    return [new HighlightedCodeReplacer()]
-  }
-}
diff --git a/src/components/markdown-renderer/markdown-extension/image/proxy-image-markdown-extension.ts b/src/components/markdown-renderer/markdown-extension/image/proxy-image-markdown-extension.ts
deleted file mode 100644
index 7cafe1f5d..000000000
--- a/src/components/markdown-renderer/markdown-extension/image/proxy-image-markdown-extension.ts
+++ /dev/null
@@ -1,23 +0,0 @@
-/*
- * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
- *
- * SPDX-License-Identifier: AGPL-3.0-only
- */
-
-import { MarkdownExtension } from '../markdown-extension'
-import type { ComponentReplacer } from '../../replace-components/component-replacer'
-import type { ImageClickHandler } from './proxy-image-replacer'
-import { ProxyImageReplacer } from './proxy-image-replacer'
-
-/**
- * Adds support for image lightbox and image proxy redirection.
- */
-export class ProxyImageMarkdownExtension extends MarkdownExtension {
-  constructor(private onImageClick?: ImageClickHandler) {
-    super()
-  }
-
-  buildReplacers(): ComponentReplacer[] {
-    return [new ProxyImageReplacer(this.onImageClick)]
-  }
-}
diff --git a/src/components/markdown-renderer/markdown-extension/legacy-short-codes/legacy-shortcodes-markdown-extension.ts b/src/components/markdown-renderer/markdown-extension/legacy-short-codes/legacy-shortcodes-markdown-extension.ts
deleted file mode 100644
index 0de7707d7..000000000
--- a/src/components/markdown-renderer/markdown-extension/legacy-short-codes/legacy-shortcodes-markdown-extension.ts
+++ /dev/null
@@ -1,45 +0,0 @@
-/*
- * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
- *
- * SPDX-License-Identifier: AGPL-3.0-only
- */
-
-import { MarkdownExtension } from '../markdown-extension'
-import type MarkdownIt from 'markdown-it'
-import { legacyPdfRegex, legacyPdfShortCode } from './replace-legacy-pdf-short-code'
-import { legacySlideshareRegex, legacySlideshareShortCode } from './replace-legacy-slideshare-short-code'
-import { legacySpeakerdeckRegex, legacySpeakerdeckShortCode } from './replace-legacy-speakerdeck-short-code'
-import { SingleLineRegexLinter } from '../../../editor-page/editor-pane/linter/single-line-regex-linter'
-import type { Linter } from '../../../editor-page/editor-pane/linter/linter'
-import { t } from 'i18next'
-
-/**
- * Adds support for legacy shortcodes (pdf, slideshare and speakerdeck) by replacing them with anchor elements.
- */
-export class LegacyShortcodesMarkdownExtension extends MarkdownExtension {
-  public configureMarkdownIt(markdownIt: MarkdownIt): void {
-    legacyPdfShortCode(markdownIt)
-    legacySlideshareShortCode(markdownIt)
-    legacySpeakerdeckShortCode(markdownIt)
-  }
-
-  public buildLinter(): Linter[] {
-    return [
-      new SingleLineRegexLinter(
-        legacySpeakerdeckRegex,
-        t('editor.linter.shortcode', { shortcode: 'SpeakerDeck' }),
-        (match: string) => `https://speakerdeck.com/${match}`
-      ),
-      new SingleLineRegexLinter(
-        legacySlideshareRegex,
-        t('editor.linter.shortcode', { shortcode: 'SlideShare' }),
-        (match: string) => `https://www.slideshare.net/${match}`
-      ),
-      new SingleLineRegexLinter(
-        legacyPdfRegex,
-        t('editor.linter.shortcode', { shortcode: 'PDF' }),
-        (match: string) => match
-      )
-    ]
-  }
-}
diff --git a/src/components/markdown-renderer/markdown-extension/markdown-extension-collection.ts b/src/components/markdown-renderer/markdown-extension/markdown-extension-collection.ts
deleted file mode 100644
index cf7d3969b..000000000
--- a/src/components/markdown-renderer/markdown-extension/markdown-extension-collection.ts
+++ /dev/null
@@ -1,57 +0,0 @@
-/*
- * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
- *
- * SPDX-License-Identifier: AGPL-3.0-only
- */
-
-import type { MarkdownExtension } from './markdown-extension'
-import type { ComponentReplacer } from '../replace-components/component-replacer'
-import type { Document } from 'domhandler'
-import type MarkdownIt from 'markdown-it'
-import { SanitizerMarkdownExtension } from './sanitizer/sanitizer-markdown-extension'
-
-/**
- * Contains multiple {@link MarkdownExtension} and uses them to configure parts of the renderer.
- */
-export class MarkdownExtensionCollection {
-  private extensions: MarkdownExtension[]
-
-  public constructor(additionalExtensions: MarkdownExtension[]) {
-    const tagWhiteLists = additionalExtensions.flatMap((extension) => extension.buildTagNameAllowList())
-
-    this.extensions = [...additionalExtensions, new SanitizerMarkdownExtension(tagWhiteLists)]
-  }
-
-  /**
-   * Configures the given {@link MarkdownIt markdown-it instance} using every saved {@link MarkdownExtension extension}.
-   *
-   * @param markdownIt The markdown-it instance to configure.
-   */
-  public configureMarkdownIt(markdownIt: MarkdownIt): void {
-    this.extensions.forEach((extension) => markdownIt.use((markdownIt) => extension.configureMarkdownIt(markdownIt)))
-    this.extensions.forEach((extension) =>
-      markdownIt.use((markdownIt) => extension.configureMarkdownItPost(markdownIt))
-    )
-  }
-
-  /**
-   * Creates a node processor that applies the node processor of every saved {@link MarkdownExtension extension}.
-   *
-   * @return the created node processor function
-   */
-  public buildFlatNodeProcessor(): (document: Document) => Document {
-    return this.extensions
-      .flatMap((extension) => extension.buildNodeProcessors())
-      .reduce(
-        (state, processor) => (document: Document) => state(processor.process(document)),
-        (document: Document) => document
-      )
-  }
-
-  /**
-   * Collects all {@link ComponentReplacer component replacers} from all saved {@link MarkdownExtension extension}.
-   */
-  public buildReplacers(): ComponentReplacer[] {
-    return this.extensions.flatMap((extension) => extension.buildReplacers())
-  }
-}
diff --git a/src/components/markdown-renderer/markdown-extension/mermaid/mermaid-markdown-extension.ts b/src/components/markdown-renderer/markdown-extension/mermaid/mermaid-markdown-extension.ts
deleted file mode 100644
index 4218b0531..000000000
--- a/src/components/markdown-renderer/markdown-extension/mermaid/mermaid-markdown-extension.ts
+++ /dev/null
@@ -1,19 +0,0 @@
-/*
- * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
- *
- * SPDX-License-Identifier: AGPL-3.0-only
- */
-
-import { CodeBlockComponentReplacer } from '../../replace-components/code-block-component-replacer'
-import type { ComponentReplacer } from '../../replace-components/component-replacer'
-import { MermaidChart } from './mermaid-chart'
-import { CodeBlockMarkdownExtension } from '../code-block-markdown-extension/code-block-markdown-extension'
-
-/**
- * Adds support for chart rendering using mermaid to the markdown rendering using code fences with "mermaid" as language.
- */
-export class MermaidMarkdownExtension extends CodeBlockMarkdownExtension {
-  public buildReplacers(): ComponentReplacer[] {
-    return [new CodeBlockComponentReplacer(MermaidChart, 'mermaid')]
-  }
-}
diff --git a/src/components/markdown-renderer/markdown-extension/sequence-diagram/sequence-diagram-markdown-extension.ts b/src/components/markdown-renderer/markdown-extension/sequence-diagram/sequence-diagram-markdown-extension.ts
deleted file mode 100644
index a4846774c..000000000
--- a/src/components/markdown-renderer/markdown-extension/sequence-diagram/sequence-diagram-markdown-extension.ts
+++ /dev/null
@@ -1,26 +0,0 @@
-/*
- * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
- *
- * SPDX-License-Identifier: AGPL-3.0-only
- */
-
-import { CodeBlockComponentReplacer } from '../../replace-components/code-block-component-replacer'
-import type { ComponentReplacer } from '../../replace-components/component-replacer'
-import { SequenceDiagram } from './sequence-diagram'
-import { CodeBlockMarkdownExtension } from '../code-block-markdown-extension/code-block-markdown-extension'
-import type { Linter } from '../../../editor-page/editor-pane/linter/linter'
-import { SingleLineRegexLinter } from '../../../editor-page/editor-pane/linter/single-line-regex-linter'
-import { t } from 'i18next'
-
-/**
- * Adds legacy support for sequence diagram to the markdown rendering using code fences with "sequence" as language.
- */
-export class SequenceDiagramMarkdownExtension extends CodeBlockMarkdownExtension {
-  public buildReplacers(): ComponentReplacer[] {
-    return [new CodeBlockComponentReplacer(SequenceDiagram, 'sequence')]
-  }
-
-  public buildLinter(): Linter[] {
-    return [new SingleLineRegexLinter(/```sequence/, t('editor.linter.sequence'), () => '```mermaid\nsequenceDiagram')]
-  }
-}
diff --git a/src/components/markdown-renderer/markdown-extension/task-list/task-list-replacer.tsx b/src/components/markdown-renderer/markdown-extension/task-list/task-list-replacer.tsx
deleted file mode 100644
index 26a4f894a..000000000
--- a/src/components/markdown-renderer/markdown-extension/task-list/task-list-replacer.tsx
+++ /dev/null
@@ -1,41 +0,0 @@
-/*
- * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
- *
- * SPDX-License-Identifier: AGPL-3.0-only
- */
-
-import type { Element } from 'domhandler'
-import React from 'react'
-import type { NodeReplacement } from '../../replace-components/component-replacer'
-import { ComponentReplacer, DO_NOT_REPLACE } from '../../replace-components/component-replacer'
-import { TaskListCheckbox } from './task-list-checkbox'
-
-export type TaskCheckedChangeHandler = (lineInMarkdown: number, checked: boolean) => void
-
-/**
- * Detects task lists and renders them as checkboxes that execute a callback if clicked.
- */
-export class TaskListReplacer extends ComponentReplacer {
-  onTaskCheckedChange?: (lineInMarkdown: number, checked: boolean) => void
-
-  constructor(onTaskCheckedChange?: TaskCheckedChangeHandler) {
-    super()
-    this.onTaskCheckedChange = (lineInMarkdown, checked) => onTaskCheckedChange?.(lineInMarkdown, checked)
-  }
-
-  public replace(node: Element): NodeReplacement {
-    if (node.attribs?.class !== 'task-list-item-checkbox') {
-      return DO_NOT_REPLACE
-    }
-    const lineInMarkdown = Number(node.attribs['data-line'])
-    return isNaN(lineInMarkdown) ? (
-      DO_NOT_REPLACE
-    ) : (
-      <TaskListCheckbox
-        onTaskCheckedChange={this.onTaskCheckedChange}
-        checked={node.attribs.checked !== undefined}
-        lineInMarkdown={lineInMarkdown}
-      />
-    )
-  }
-}
diff --git a/src/components/markdown-renderer/markdown-extension/vega-lite/vega-lite-markdown-extension.ts b/src/components/markdown-renderer/markdown-extension/vega-lite/vega-lite-markdown-extension.ts
deleted file mode 100644
index 311a88d45..000000000
--- a/src/components/markdown-renderer/markdown-extension/vega-lite/vega-lite-markdown-extension.ts
+++ /dev/null
@@ -1,19 +0,0 @@
-/*
- * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
- *
- * SPDX-License-Identifier: AGPL-3.0-only
- */
-
-import { CodeBlockComponentReplacer } from '../../replace-components/code-block-component-replacer'
-import type { ComponentReplacer } from '../../replace-components/component-replacer'
-import { VegaLiteChart } from './vega-lite-chart'
-import { CodeBlockMarkdownExtension } from '../code-block-markdown-extension/code-block-markdown-extension'
-
-/**
- * Adds support for chart rendering using vega lite to the markdown rendering using code fences with "vega-lite" as language.
- */
-export class VegaLiteMarkdownExtension extends CodeBlockMarkdownExtension {
-  public buildReplacers(): ComponentReplacer[] {
-    return [new CodeBlockComponentReplacer(VegaLiteChart, 'vega-lite')]
-  }
-}
diff --git a/src/components/markdown-renderer/markdown-extension/vimeo/vimeo-markdown-extension.ts b/src/components/markdown-renderer/markdown-extension/vimeo/vimeo-markdown-extension.ts
deleted file mode 100644
index e0d96a676..000000000
--- a/src/components/markdown-renderer/markdown-extension/vimeo/vimeo-markdown-extension.ts
+++ /dev/null
@@ -1,46 +0,0 @@
-/*
- * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
- *
- * SPDX-License-Identifier: AGPL-3.0-only
- */
-
-import { MarkdownExtension } from '../markdown-extension'
-import type MarkdownIt from 'markdown-it'
-import type { ComponentReplacer } from '../../replace-components/component-replacer'
-import { CustomTagWithIdComponentReplacer } from '../../replace-components/custom-tag-with-id-component-replacer'
-import { replaceVimeoLinkMarkdownItPlugin } from './replace-vimeo-link'
-import { VimeoFrame } from './vimeo-frame'
-import { legacyVimeoRegex, replaceLegacyVimeoShortCodeMarkdownItPlugin } from './replace-legacy-vimeo-short-code'
-import type { Linter } from '../../../editor-page/editor-pane/linter/linter'
-import { SingleLineRegexLinter } from '../../../editor-page/editor-pane/linter/single-line-regex-linter'
-import { t } from 'i18next'
-
-/**
- * Adds vimeo video embeddings using link detection and the legacy vimeo short code syntax.
- */
-export class VimeoMarkdownExtension extends MarkdownExtension {
-  public static readonly tagName = 'app-vimeo'
-
-  public configureMarkdownIt(markdownIt: MarkdownIt): void {
-    replaceLegacyVimeoShortCodeMarkdownItPlugin(markdownIt)
-    replaceVimeoLinkMarkdownItPlugin(markdownIt)
-  }
-
-  public buildReplacers(): ComponentReplacer[] {
-    return [new CustomTagWithIdComponentReplacer(VimeoFrame, VimeoMarkdownExtension.tagName)]
-  }
-
-  public buildTagNameAllowList(): string[] {
-    return [VimeoMarkdownExtension.tagName]
-  }
-
-  public buildLinter(): Linter[] {
-    return [
-      new SingleLineRegexLinter(
-        legacyVimeoRegex,
-        t('editor.linter.shortcode', { shortcode: 'Vimeo' }),
-        (match: string) => `https://player.vimeo.com/video/${match}`
-      )
-    ]
-  }
-}
diff --git a/src/components/markdown-renderer/markdown-extension/youtube/youtube-markdown-extension.ts b/src/components/markdown-renderer/markdown-extension/youtube/youtube-markdown-extension.ts
deleted file mode 100644
index e2eac2c10..000000000
--- a/src/components/markdown-renderer/markdown-extension/youtube/youtube-markdown-extension.ts
+++ /dev/null
@@ -1,46 +0,0 @@
-/*
- * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
- *
- * SPDX-License-Identifier: AGPL-3.0-only
- */
-
-import { MarkdownExtension } from '../markdown-extension'
-import { replaceYouTubeLinkMarkdownItPlugin } from './replace-youtube-link'
-import { legacyYouTubeRegex, replaceLegacyYoutubeShortCodeMarkdownItPlugin } from './replace-legacy-youtube-short-code'
-import type MarkdownIt from 'markdown-it'
-import type { ComponentReplacer } from '../../replace-components/component-replacer'
-import { CustomTagWithIdComponentReplacer } from '../../replace-components/custom-tag-with-id-component-replacer'
-import { YouTubeFrame } from './youtube-frame'
-import type { Linter } from '../../../editor-page/editor-pane/linter/linter'
-import { SingleLineRegexLinter } from '../../../editor-page/editor-pane/linter/single-line-regex-linter'
-import { t } from 'i18next'
-
-/**
- * Adds YouTube video embeddings using link detection and the legacy YouTube short code syntax.
- */
-export class YoutubeMarkdownExtension extends MarkdownExtension {
-  public static readonly tagName = 'app-youtube'
-
-  public configureMarkdownIt(markdownIt: MarkdownIt): void {
-    replaceYouTubeLinkMarkdownItPlugin(markdownIt)
-    replaceLegacyYoutubeShortCodeMarkdownItPlugin(markdownIt)
-  }
-
-  public buildReplacers(): ComponentReplacer[] {
-    return [new CustomTagWithIdComponentReplacer(YouTubeFrame, YoutubeMarkdownExtension.tagName)]
-  }
-
-  public buildTagNameAllowList(): string[] {
-    return [YoutubeMarkdownExtension.tagName]
-  }
-
-  public buildLinter(): Linter[] {
-    return [
-      new SingleLineRegexLinter(
-        legacyYouTubeRegex,
-        t('editor.linter.shortcode', { shortcode: 'YouTube' }),
-        (match: string) => `https://www.youtube.com/watch?v=${match}`
-      )
-    ]
-  }
-}
diff --git a/src/components/markdown-renderer/replace-components/click-shield/click-shield.tsx b/src/components/markdown-renderer/replace-components/click-shield/click-shield.tsx
index f019be895..8d94f7f68 100644
--- a/src/components/markdown-renderer/replace-components/click-shield/click-shield.tsx
+++ b/src/components/markdown-renderer/replace-components/click-shield/click-shield.tsx
@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
  *
  * SPDX-License-Identifier: AGPL-3.0-only
  */
@@ -15,7 +15,7 @@ import type { Property } from 'csstype'
 import type { PropsWithDataCypressId } from '../../../../utils/cypress-attribute'
 import { cypressId } from '../../../../utils/cypress-attribute'
 import { ForkAwesomeIcon } from '../../../common/fork-awesome/fork-awesome-icon'
-import { ProxyImageFrame } from '../../markdown-extension/image/proxy-image-frame'
+import { ProxyImageFrame } from '../../extensions/image/proxy-image-frame'
 
 const log = new Logger('OneClickEmbedding')
 
diff --git a/src/components/markdown-renderer/slideshow-markdown-renderer.tsx b/src/components/markdown-renderer/slideshow-markdown-renderer.tsx
index 0460482b3..97eafb1e2 100644
--- a/src/components/markdown-renderer/slideshow-markdown-renderer.tsx
+++ b/src/components/markdown-renderer/slideshow-markdown-renderer.tsx
@@ -7,15 +7,13 @@
 import React, { useEffect, useMemo, useRef } from 'react'
 import { useConvertMarkdownToReactDom } from './hooks/use-convert-markdown-to-react-dom'
 import { useExtractFirstHeadline } from './hooks/use-extract-first-headline'
-import type { TocAst } from 'markdown-it-toc-done-right'
-import { useOnRefChange } from './hooks/use-on-ref-change'
 import { REVEAL_STATUS, useReveal } from './hooks/use-reveal'
 import type { ScrollProps } from '../editor-page/synced-scroll/scroll-props'
 import type { CommonMarkdownRendererProps } from './common-markdown-renderer-props'
 import { LoadingSlide } from './loading-slide'
-import { RevealMarkdownExtension } from './markdown-extension/reveal/reveal-markdown-extension'
 import { useMarkdownExtensions } from './hooks/use-markdown-extensions'
 import type { SlideOptions } from '../../redux/note-details/types/slide-show-options'
+import { RevealMarkdownExtension } from './extensions/reveal/reveal-markdown-extension'
 
 export interface SlideshowMarkdownRendererProps extends CommonMarkdownRendererProps {
   slideOptions?: SlideOptions
@@ -39,26 +37,19 @@ export const SlideshowMarkdownRenderer: React.FC<SlideshowMarkdownRendererProps
   className,
   markdownContentLines,
   onFirstHeadingChange,
-  onTaskCheckedChange,
-  onTocChange,
   baseUrl,
-  onImageClick,
   newlinesAreBreaks,
   slideOptions
 }) => {
   const markdownBodyRef = useRef<HTMLDivElement>(null)
-  const tocAst = useRef<TocAst>()
 
   const extensions = useMarkdownExtensions(
     baseUrl,
     undefined,
-    useMemo(() => [new RevealMarkdownExtension()], []),
-    onTaskCheckedChange,
-    onImageClick,
-    onTocChange
+    useMemo(() => [new RevealMarkdownExtension()], [])
   )
 
-  const markdownReactDom = useConvertMarkdownToReactDom(markdownContentLines, extensions, newlinesAreBreaks)
+  const markdownReactDom = useConvertMarkdownToReactDom(markdownContentLines, extensions, newlinesAreBreaks, true)
   const revealStatus = useReveal(markdownContentLines, slideOptions)
 
   const extractFirstHeadline = useExtractFirstHeadline(markdownBodyRef, onFirstHeadingChange)
@@ -68,8 +59,6 @@ export const SlideshowMarkdownRenderer: React.FC<SlideshowMarkdownRendererProps
     }
   }, [extractFirstHeadline, markdownContentLines, revealStatus])
 
-  useOnRefChange(tocAst, onTocChange)
-
   const slideShowDOM = useMemo(
     () => (revealStatus === REVEAL_STATUS.INITIALISED ? markdownReactDom : <LoadingSlide />),
     [markdownReactDom, revealStatus]
@@ -83,5 +72,3 @@ export const SlideshowMarkdownRenderer: React.FC<SlideshowMarkdownRendererProps
     </div>
   )
 }
-
-export default SlideshowMarkdownRenderer
diff --git a/src/components/markdown-renderer/test-utils/test-markdown-renderer.tsx b/src/components/markdown-renderer/test-utils/test-markdown-renderer.tsx
index dc47f0a59..873e63c89 100644
--- a/src/components/markdown-renderer/test-utils/test-markdown-renderer.tsx
+++ b/src/components/markdown-renderer/test-utils/test-markdown-renderer.tsx
@@ -6,19 +6,19 @@
 
 import React, { useMemo } from 'react'
 import { useConvertMarkdownToReactDom } from '../hooks/use-convert-markdown-to-react-dom'
-import type { MarkdownExtension } from '../markdown-extension/markdown-extension'
 import { StoreProvider } from '../../../redux/store-provider'
+import type { MarkdownRendererExtension } from '../extensions/base/markdown-renderer-extension'
 
 export interface SimpleMarkdownRendererProps {
   content: string
-  extensions: MarkdownExtension[]
+  extensions: MarkdownRendererExtension[]
 }
 
 /**
  * A markdown renderer for tests.
  *
  * @param content The content to be rendered.
- * @param extensions The {@link MarkdownExtension MarkdownExtensions} to use for rendering.
+ * @param extensions The {@link MarkdownRendererExtension MarkdownExtensions} to use for rendering.
  */
 export const TestMarkdownRenderer: React.FC<SimpleMarkdownRendererProps> = ({ content, extensions }) => {
   const lines = useMemo(() => content.split('\n'), [content])
diff --git a/src/components/markdown-renderer/utils/calculate-line-marker-positions.ts b/src/components/markdown-renderer/utils/calculate-line-marker-positions.ts
index 3f6b6e5e1..4a5a0311f 100644
--- a/src/components/markdown-renderer/utils/calculate-line-marker-positions.ts
+++ b/src/components/markdown-renderer/utils/calculate-line-marker-positions.ts
@@ -7,9 +7,9 @@
 import equal from 'fast-deep-equal'
 import type { RefObject } from 'react'
 import { useCallback, useEffect, useRef } from 'react'
-import type { LineMarkerPosition } from '../markdown-extension/linemarker/types'
-import type { LineMarkers } from '../markdown-extension/linemarker/add-line-marker-markdown-it-plugin'
 import useResizeObserver from '@react-hook/resize-observer'
+import type { LineMarkerPosition } from '../extensions/linemarker/types'
+import type { LineMarkers } from '../extensions/linemarker/add-line-marker-markdown-it-plugin'
 
 const calculateLineMarkerPositions = (
   documentElement: HTMLDivElement,
diff --git a/src/components/markdown-renderer/utils/line-id-mapper.ts b/src/components/markdown-renderer/utils/line-id-mapper.ts
index 097eb6eeb..fb1bfa9f1 100644
--- a/src/components/markdown-renderer/utils/line-id-mapper.ts
+++ b/src/components/markdown-renderer/utils/line-id-mapper.ts
@@ -4,9 +4,9 @@
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
-import type { LineWithId } from '../markdown-extension/linemarker/types'
 import type { ArrayChange } from 'diff'
 import { diffArrays } from 'diff'
+import type { LineWithId } from '../extensions/linemarker/types'
 
 type NewLine = string
 type LineChange = ArrayChange<NewLine | LineWithId>
diff --git a/src/components/markdown-renderer/utils/node-to-react-transformer.tsx b/src/components/markdown-renderer/utils/node-to-react-transformer.tsx
index b3cd749e2..c8cb594ac 100644
--- a/src/components/markdown-renderer/utils/node-to-react-transformer.tsx
+++ b/src/components/markdown-renderer/utils/node-to-react-transformer.tsx
@@ -10,9 +10,9 @@ import { convertNodeToReactElement } from '@hedgedoc/html-to-react/dist/convertN
 import type { ComponentReplacer, NodeReplacement, ValidReactDomElement } from '../replace-components/component-replacer'
 import { DO_NOT_REPLACE } from '../replace-components/component-replacer'
 import React from 'react'
-import type { LineWithId } from '../markdown-extension/linemarker/types'
 import { Optional } from '@mrdrogdrog/optional'
-import { LinemarkerMarkdownExtension } from '../markdown-extension/linemarker/linemarker-markdown-extension'
+import { LinemarkerMarkdownExtension } from '../extensions/linemarker/linemarker-markdown-extension'
+import type { LineWithId } from '../extensions/linemarker/types'
 
 type LineIndexPair = [startLineIndex: number, endLineIndex: number]
 
diff --git a/src/components/render-page/document-toc-sidebar.tsx b/src/components/render-page/document-toc-sidebar.tsx
new file mode 100644
index 000000000..11e87f245
--- /dev/null
+++ b/src/components/render-page/document-toc-sidebar.tsx
@@ -0,0 +1,31 @@
+/*
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import React, { useState } from 'react'
+import styles from './markdown-document.module.scss'
+import { ShowIf } from '../common/show-if/show-if'
+import { WidthBasedTableOfContents } from './width-based-table-of-contents'
+import type { TocAst } from 'markdown-it-toc-done-right'
+import { useExtensionEventEmitterHandler } from '../markdown-renderer/hooks/use-extension-event-emitter'
+import { TableOfContentsMarkdownExtension } from '../markdown-renderer/extensions/table-of-contents-markdown-extension'
+
+export interface DocumentTocSidebarProps {
+  width: number
+  disableToc: boolean
+  baseUrl: string
+}
+
+export const DocumentTocSidebar: React.FC<DocumentTocSidebarProps> = ({ disableToc, width, baseUrl }) => {
+  const [tocAst, setTocAst] = useState<TocAst>()
+  useExtensionEventEmitterHandler(TableOfContentsMarkdownExtension.EVENT_NAME, setTocAst)
+  return (
+    <div className={`${styles['markdown-document-side']} pt-4`}>
+      <ShowIf condition={!!tocAst && !disableToc}>
+        <WidthBasedTableOfContents tocAst={tocAst as TocAst} baseUrl={baseUrl} width={width} />
+      </ShowIf>
+    </div>
+  )
+}
diff --git a/src/components/render-page/hooks/sync-scroll/use-document-sync-scrolling.ts b/src/components/render-page/hooks/sync-scroll/use-document-sync-scrolling.ts
index d655af7b0..144343346 100644
--- a/src/components/render-page/hooks/sync-scroll/use-document-sync-scrolling.ts
+++ b/src/components/render-page/hooks/sync-scroll/use-document-sync-scrolling.ts
@@ -6,10 +6,10 @@
 
 import type React from 'react'
 import { useCallback, useMemo, useState } from 'react'
-import type { LineMarkerPosition } from '../../../markdown-renderer/markdown-extension/linemarker/types'
 import type { ScrollState } from '../../../editor-page/synced-scroll/scroll-props'
 import { useOnUserScroll } from './use-on-user-scroll'
 import { useScrollToLineMark } from './use-scroll-to-line-mark'
+import type { LineMarkerPosition } from '../../../markdown-renderer/extensions/linemarker/types'
 
 /**
  * Synchronizes the scroll status of the given container with the given scroll state and posts changes if the user scrolls.
diff --git a/src/components/render-page/hooks/sync-scroll/use-on-user-scroll.ts b/src/components/render-page/hooks/sync-scroll/use-on-user-scroll.ts
index 9a2886d05..9bf467b0e 100644
--- a/src/components/render-page/hooks/sync-scroll/use-on-user-scroll.ts
+++ b/src/components/render-page/hooks/sync-scroll/use-on-user-scroll.ts
@@ -6,8 +6,8 @@
 
 import type React from 'react'
 import { useCallback } from 'react'
-import type { LineMarkerPosition } from '../../../markdown-renderer/markdown-extension/linemarker/types'
 import type { ScrollState } from '../../../editor-page/synced-scroll/scroll-props'
+import type { LineMarkerPosition } from '../../../markdown-renderer/extensions/linemarker/types'
 
 /**
  * Provides a callback to handle user scrolling.
diff --git a/src/components/render-page/hooks/sync-scroll/use-scroll-to-line-mark.ts b/src/components/render-page/hooks/sync-scroll/use-scroll-to-line-mark.ts
index c8eee1625..702684b24 100644
--- a/src/components/render-page/hooks/sync-scroll/use-scroll-to-line-mark.ts
+++ b/src/components/render-page/hooks/sync-scroll/use-scroll-to-line-mark.ts
@@ -6,9 +6,9 @@
 
 import type { RefObject } from 'react'
 import { useCallback, useEffect, useRef } from 'react'
-import type { LineMarkerPosition } from '../../../markdown-renderer/markdown-extension/linemarker/types'
 import type { ScrollState } from '../../../editor-page/synced-scroll/scroll-props'
 import { findLineMarks } from '../../../editor-page/synced-scroll/utils'
+import type { LineMarkerPosition } from '../../../markdown-renderer/extensions/linemarker/types'
 
 /**
  * Scrolls the given container to the correct {@link LineMarkerPosition}.
diff --git a/src/components/render-page/hooks/use-image-click-handler.ts b/src/components/render-page/hooks/use-image-click-handler.ts
deleted file mode 100644
index 4ebcf8d4b..000000000
--- a/src/components/render-page/hooks/use-image-click-handler.ts
+++ /dev/null
@@ -1,37 +0,0 @@
-/*
- * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
- *
- * SPDX-License-Identifier: AGPL-3.0-only
- */
-
-import type React from 'react'
-import { useCallback } from 'react'
-import type { ImageClickHandler } from '../../markdown-renderer/markdown-extension/image/proxy-image-replacer'
-import type { RendererToEditorCommunicator } from '../window-post-message-communicator/renderer-to-editor-communicator'
-import { CommunicationMessageType } from '../window-post-message-communicator/rendering-message'
-
-/**
- * Generates a callback to send information about a clicked image from the iframe back to the editor.
- *
- * @param iframeCommunicator The communicator to send the message with.
- * @return The callback to give to on onClick handler
- */
-export const useImageClickHandler = (iframeCommunicator: RendererToEditorCommunicator): ImageClickHandler => {
-  return useCallback(
-    (event: React.MouseEvent<HTMLImageElement, MouseEvent>) => {
-      const image = event.target as HTMLImageElement
-      if (image.src === '') {
-        return
-      }
-      iframeCommunicator.sendMessageToOtherSide({
-        type: CommunicationMessageType.IMAGE_CLICKED,
-        details: {
-          src: image.src,
-          alt: image.alt,
-          title: image.title
-        }
-      })
-    },
-    [iframeCommunicator]
-  )
-}
diff --git a/src/components/render-page/iframe-markdown-renderer.tsx b/src/components/render-page/iframe-markdown-renderer.tsx
index 5f84df853..802424fae 100644
--- a/src/components/render-page/iframe-markdown-renderer.tsx
+++ b/src/components/render-page/iframe-markdown-renderer.tsx
@@ -4,19 +4,19 @@
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
-import React, { useCallback, useRef, useState } from 'react'
+import React, { useCallback, useEffect, useMemo, useRef, useState } from 'react'
 import type { ScrollState } from '../editor-page/synced-scroll/scroll-props'
 import type { BaseConfiguration } from './window-post-message-communicator/rendering-message'
 import { CommunicationMessageType, RendererType } from './window-post-message-communicator/rendering-message'
 import { setDarkMode } from '../../redux/dark-mode/methods'
-import type { ImageClickHandler } from '../markdown-renderer/markdown-extension/image/proxy-image-replacer'
-import { useImageClickHandler } from './hooks/use-image-click-handler'
 import { MarkdownDocument } from './markdown-document'
 import { countWords } from './word-counter'
 import { useRendererToEditorCommunicator } from '../editor-page/render-context/renderer-to-editor-communicator-context-provider'
 import { useRendererReceiveHandler } from './window-post-message-communicator/hooks/use-renderer-receive-handler'
 import { SlideshowMarkdownRenderer } from '../markdown-renderer/slideshow-markdown-renderer'
 import type { SlideOptions } from '../../redux/note-details/types/slide-show-options'
+import EventEmitter2 from 'eventemitter2'
+import { eventEmitterContext } from '../markdown-renderer/hooks/use-extension-event-emitter'
 
 /**
  * Wraps the markdown rendering in an iframe.
@@ -74,17 +74,6 @@ export const IframeMarkdownRenderer: React.FC = () => {
     }, [communicator])
   )
 
-  const onTaskCheckedChange = useCallback(
-    (lineInMarkdown: number, checked: boolean) => {
-      communicator.sendMessageToOtherSide({
-        type: CommunicationMessageType.ON_TASK_CHECKBOX_CHANGE,
-        checked,
-        lineInMarkdown
-      })
-    },
-    [communicator]
-  )
-
   const onFirstHeadingChange = useCallback(
     (firstHeading?: string) => {
       communicator.sendMessageToOtherSide({
@@ -115,8 +104,6 @@ export const IframeMarkdownRenderer: React.FC = () => {
     [communicator]
   )
 
-  const onImageClick: ImageClickHandler = useImageClickHandler(communicator)
-
   const onHeightChange = useCallback(
     (height: number) => {
       communicator.sendMessageToOtherSide({
@@ -127,51 +114,75 @@ export const IframeMarkdownRenderer: React.FC = () => {
     [communicator]
   )
 
-  if (!baseConfiguration) {
-    return (
-      <span>This is the render endpoint. If you can read this text then please check your HedgeDoc configuration.</span>
-    )
-  }
+  const renderer = useMemo(() => {
+    if (!baseConfiguration) {
+      return (
+        <span>
+          This is the render endpoint. If you can read this text then please check your HedgeDoc configuration.
+        </span>
+      )
+    }
 
-  switch (baseConfiguration.rendererType) {
-    case RendererType.DOCUMENT:
-      return (
-        <MarkdownDocument
-          additionalOuterContainerClasses={'vh-100 bg-light'}
-          markdownContentLines={markdownContentLines}
-          onTaskCheckedChange={onTaskCheckedChange}
-          onFirstHeadingChange={onFirstHeadingChange}
-          onMakeScrollSource={onMakeScrollSource}
-          scrollState={scrollState}
-          onScroll={onScroll}
-          baseUrl={baseConfiguration.baseUrl}
-          onImageClick={onImageClick}
-        />
-      )
-    case RendererType.SLIDESHOW:
-      return (
-        <SlideshowMarkdownRenderer
-          markdownContentLines={markdownContentLines}
-          baseUrl={baseConfiguration.baseUrl}
-          onFirstHeadingChange={onFirstHeadingChange}
-          onImageClick={onImageClick}
-          scrollState={scrollState}
-          slideOptions={slideOptions}
-        />
-      )
-    case RendererType.MOTD:
-    case RendererType.INTRO:
-      return (
-        <MarkdownDocument
-          additionalOuterContainerClasses={'vh-100 bg-light overflow-y-hidden'}
-          markdownContentLines={markdownContentLines}
-          baseUrl={baseConfiguration.baseUrl}
-          onImageClick={onImageClick}
-          disableToc={true}
-          onHeightChange={onHeightChange}
-        />
-      )
-    default:
-      return null
-  }
+    switch (baseConfiguration.rendererType) {
+      case RendererType.DOCUMENT:
+        return (
+          <MarkdownDocument
+            additionalOuterContainerClasses={'vh-100 bg-light'}
+            markdownContentLines={markdownContentLines}
+            onFirstHeadingChange={onFirstHeadingChange}
+            onMakeScrollSource={onMakeScrollSource}
+            scrollState={scrollState}
+            onScroll={onScroll}
+            baseUrl={baseConfiguration.baseUrl}
+            onHeightChange={onHeightChange}
+          />
+        )
+      case RendererType.SLIDESHOW:
+        return (
+          <SlideshowMarkdownRenderer
+            markdownContentLines={markdownContentLines}
+            baseUrl={baseConfiguration.baseUrl}
+            onFirstHeadingChange={onFirstHeadingChange}
+            scrollState={scrollState}
+            slideOptions={slideOptions}
+          />
+        )
+      case RendererType.MOTD:
+      case RendererType.INTRO:
+        return (
+          <MarkdownDocument
+            additionalOuterContainerClasses={'vh-100 bg-light overflow-y-hidden'}
+            markdownContentLines={markdownContentLines}
+            baseUrl={baseConfiguration.baseUrl}
+            disableToc={true}
+            onHeightChange={onHeightChange}
+          />
+        )
+      default:
+        return null
+    }
+  }, [
+    baseConfiguration,
+    markdownContentLines,
+    onFirstHeadingChange,
+    onHeightChange,
+    onMakeScrollSource,
+    onScroll,
+    scrollState,
+    slideOptions
+  ])
+
+  const extensionEventEmitter = useMemo(() => new EventEmitter2({ wildcard: true }), [])
+
+  useEffect(() => {
+    extensionEventEmitter.onAny((event, values) => {
+      communicator.sendMessageToOtherSide({
+        type: CommunicationMessageType.EXTENSION_EVENT,
+        eventName: typeof event === 'object' ? event.join('.') : event,
+        payload: values
+      })
+    })
+  }, [communicator, extensionEventEmitter])
+
+  return <eventEmitterContext.Provider value={extensionEventEmitter}>{renderer}</eventEmitterContext.Provider>
 }
diff --git a/src/components/render-page/markdown-document.tsx b/src/components/render-page/markdown-document.tsx
index 696a7c814..32dd305e3 100644
--- a/src/components/render-page/markdown-document.tsx
+++ b/src/components/render-page/markdown-document.tsx
@@ -4,25 +4,20 @@
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
-import type { TocAst } from 'markdown-it-toc-done-right'
 import type { MutableRefObject } from 'react'
 import React, { useEffect, useMemo, useRef, useState } from 'react'
 import useResizeObserver from '@react-hook/resize-observer'
 import { useDocumentSyncScrolling } from './hooks/sync-scroll/use-document-sync-scrolling'
 import type { ScrollProps } from '../editor-page/synced-scroll/scroll-props'
 import { DocumentMarkdownRenderer } from '../markdown-renderer/document-markdown-renderer'
-import type { ImageClickHandler } from '../markdown-renderer/markdown-extension/image/proxy-image-replacer'
 import styles from './markdown-document.module.scss'
-import { WidthBasedTableOfContents } from './width-based-table-of-contents'
-import { ShowIf } from '../common/show-if/show-if'
 import { useApplicationState } from '../../hooks/common/use-application-state'
+import { DocumentTocSidebar } from './document-toc-sidebar'
 
 export interface RendererProps extends ScrollProps {
   onFirstHeadingChange?: (firstHeading: string | undefined) => void
-  onTaskCheckedChange?: (lineInMarkdown: number, checked: boolean) => void
   documentRenderPaneRef?: MutableRefObject<HTMLDivElement | null>
   markdownContentLines: string[]
-  onImageClick?: ImageClickHandler
   onHeightChange?: (height: number) => void
 }
 
@@ -55,10 +50,8 @@ export const MarkdownDocument: React.FC<MarkdownDocumentProps> = ({
   additionalRendererClasses,
   onFirstHeadingChange,
   onMakeScrollSource,
-  onTaskCheckedChange,
   baseUrl,
   markdownContentLines,
-  onImageClick,
   onScroll,
   scrollState,
   onHeightChange,
@@ -77,8 +70,6 @@ export const MarkdownDocument: React.FC<MarkdownDocumentProps> = ({
     setInternalDocumentRenderPaneSize(entry.contentRect)
   )
 
-  const containerWidth = internalDocumentRenderPaneSize?.width ?? 0
-  const [tocAst, setTocAst] = useState<TocAst>()
   const newlinesAreBreaks = useApplicationState((state) => state.noteDetails.frontmatter.newlinesAreBreaks)
 
   const contentLineCount = useMemo(() => markdownContentLines.length, [markdownContentLines])
@@ -106,18 +97,15 @@ export const MarkdownDocument: React.FC<MarkdownDocumentProps> = ({
           markdownContentLines={markdownContentLines}
           onFirstHeadingChange={onFirstHeadingChange}
           onLineMarkerPositionChanged={onLineMarkerPositionChanged}
-          onTaskCheckedChange={onTaskCheckedChange}
-          onTocChange={setTocAst}
           baseUrl={baseUrl}
-          onImageClick={onImageClick}
           newlinesAreBreaks={newlinesAreBreaks}
         />
       </div>
-      <div className={`${styles['markdown-document-side']} pt-4`}>
-        <ShowIf condition={!!tocAst && !disableToc}>
-          <WidthBasedTableOfContents tocAst={tocAst as TocAst} baseUrl={baseUrl} width={containerWidth} />
-        </ShowIf>
-      </div>
+      <DocumentTocSidebar
+        width={internalDocumentRenderPaneSize?.width ?? 0}
+        baseUrl={baseUrl}
+        disableToc={disableToc ?? false}
+      />
     </div>
   )
 }
diff --git a/src/components/render-page/window-post-message-communicator/rendering-message.ts b/src/components/render-page/window-post-message-communicator/rendering-message.ts
index 8763e2085..12ee861ce 100644
--- a/src/components/render-page/window-post-message-communicator/rendering-message.ts
+++ b/src/components/render-page/window-post-message-communicator/rendering-message.ts
@@ -10,18 +10,17 @@ export enum CommunicationMessageType {
   SET_MARKDOWN_CONTENT = 'SET_MARKDOWN_CONTENT',
   RENDERER_READY = 'RENDERER_READY',
   SET_DARKMODE = 'SET_DARKMODE',
-  ON_TASK_CHECKBOX_CHANGE = 'ON_TASK_CHECKBOX_CHANGE',
   ON_FIRST_HEADING_CHANGE = 'ON_FIRST_HEADING_CHANGE',
   ENABLE_RENDERER_SCROLL_SOURCE = 'ENABLE_RENDERER_SCROLL_SOURCE',
   DISABLE_RENDERER_SCROLL_SOURCE = 'DISABLE_RENDERER_SCROLL_SOURCE',
   SET_SCROLL_STATE = 'SET_SCROLL_STATE',
-  IMAGE_CLICKED = 'IMAGE_CLICKED',
   ON_HEIGHT_CHANGE = 'ON_HEIGHT_CHANGE',
   SET_BASE_CONFIGURATION = 'SET_BASE_CONFIGURATION',
   GET_WORD_COUNT = 'GET_WORD_COUNT',
   ON_WORD_COUNT_CALCULATED = 'ON_WORD_COUNT_CALCULATED',
   SET_SLIDE_OPTIONS = 'SET_SLIDE_OPTIONS',
-  IMAGE_UPLOAD = 'IMAGE_UPLOAD'
+  IMAGE_UPLOAD = 'IMAGE_UPLOAD',
+  EXTENSION_EVENT = 'EXTENSION_EVENT'
 }
 
 export interface NoPayloadMessage<TYPE extends CommunicationMessageType> {
@@ -33,6 +32,12 @@ export interface SetDarkModeMessage {
   activated: boolean
 }
 
+export interface ExtensionEvent {
+  type: CommunicationMessageType.EXTENSION_EVENT
+  eventName: string
+  payload: unknown
+}
+
 export interface ImageDetails {
   alt?: string
   src: string
@@ -56,11 +61,6 @@ export interface GetWordCountMessage {
   type: CommunicationMessageType.GET_WORD_COUNT
 }
 
-export interface ImageClickedMessage {
-  type: CommunicationMessageType.IMAGE_CLICKED
-  details: ImageDetails
-}
-
 export interface SetMarkdownContentMessage {
   type: CommunicationMessageType.SET_MARKDOWN_CONTENT
   content: string[]
@@ -71,12 +71,6 @@ export interface SetScrollStateMessage {
   scrollState: ScrollState
 }
 
-export interface OnTaskCheckboxChangeMessage {
-  type: CommunicationMessageType.ON_TASK_CHECKBOX_CHANGE
-  lineInMarkdown: number
-  checked: boolean
-}
-
 export interface OnFirstHeadingChangeMessage {
   type: CommunicationMessageType.ON_FIRST_HEADING_CHANGE
   firstHeading: string | undefined
@@ -104,15 +98,14 @@ export type CommunicationMessages =
   | SetDarkModeMessage
   | SetBaseUrlMessage
   | GetWordCountMessage
-  | ImageClickedMessage
   | SetMarkdownContentMessage
   | SetScrollStateMessage
-  | OnTaskCheckboxChangeMessage
   | OnFirstHeadingChangeMessage
   | SetSlideOptionsMessage
   | OnHeightChangeMessage
   | OnWordCountCalculatedMessage
   | ImageUploadMessage
+  | ExtensionEvent
 
 export type EditorToRendererMessageType =
   | CommunicationMessageType.SET_MARKDOWN_CONTENT
@@ -127,12 +120,11 @@ export type RendererToEditorMessageType =
   | CommunicationMessageType.RENDERER_READY
   | CommunicationMessageType.ENABLE_RENDERER_SCROLL_SOURCE
   | CommunicationMessageType.ON_FIRST_HEADING_CHANGE
-  | CommunicationMessageType.ON_TASK_CHECKBOX_CHANGE
   | CommunicationMessageType.SET_SCROLL_STATE
-  | CommunicationMessageType.IMAGE_CLICKED
   | CommunicationMessageType.ON_HEIGHT_CHANGE
   | CommunicationMessageType.ON_WORD_COUNT_CALCULATED
   | CommunicationMessageType.IMAGE_UPLOAD
+  | CommunicationMessageType.EXTENSION_EVENT
 
 export enum RendererType {
   DOCUMENT = 'document',
diff --git a/src/extensions/base/app-extension.ts b/src/extensions/base/app-extension.ts
new file mode 100644
index 000000000..d8cedd86c
--- /dev/null
+++ b/src/extensions/base/app-extension.ts
@@ -0,0 +1,26 @@
+/*
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import type { Linter } from '../../components/editor-page/editor-pane/linter/linter'
+import type { MarkdownRendererExtension } from '../../components/markdown-renderer/extensions/base/markdown-renderer-extension'
+import type React from 'react'
+import { Fragment } from 'react'
+import type EventEmitter2 from 'eventemitter2'
+
+export abstract class AppExtension {
+  // eslint-disable-next-line @typescript-eslint/no-unused-vars
+  public buildMarkdownRendererExtensions(eventEmitter?: EventEmitter2): MarkdownRendererExtension[] {
+    return []
+  }
+
+  public buildCodeMirrorLinter(): Linter[] {
+    return []
+  }
+
+  public buildEditorExtensionComponent(): React.FC {
+    return Fragment
+  }
+}
diff --git a/src/components/markdown-renderer/markdown-extension/abcjs/__snapshots__/abc-frame.test.tsx.snap b/src/extensions/extra-integrations/abcjs/__snapshots__/abc-frame.test.tsx.snap
similarity index 100%
rename from src/components/markdown-renderer/markdown-extension/abcjs/__snapshots__/abc-frame.test.tsx.snap
rename to src/extensions/extra-integrations/abcjs/__snapshots__/abc-frame.test.tsx.snap
diff --git a/src/components/markdown-renderer/markdown-extension/abcjs/__snapshots__/abcjs-markdown-extension.test.tsx.snap b/src/extensions/extra-integrations/abcjs/__snapshots__/abcjs-markdown-extension.test.tsx.snap
similarity index 100%
rename from src/components/markdown-renderer/markdown-extension/abcjs/__snapshots__/abcjs-markdown-extension.test.tsx.snap
rename to src/extensions/extra-integrations/abcjs/__snapshots__/abcjs-markdown-extension.test.tsx.snap
diff --git a/src/components/markdown-renderer/markdown-extension/abcjs/abc-frame.test.tsx b/src/extensions/extra-integrations/abcjs/abc-frame.test.tsx
similarity index 95%
rename from src/components/markdown-renderer/markdown-extension/abcjs/abc-frame.test.tsx
rename to src/extensions/extra-integrations/abcjs/abc-frame.test.tsx
index 5d9e65819..fd7cd868a 100644
--- a/src/components/markdown-renderer/markdown-extension/abcjs/abc-frame.test.tsx
+++ b/src/extensions/extra-integrations/abcjs/abc-frame.test.tsx
@@ -7,16 +7,14 @@
 import React from 'react'
 import { render, screen } from '@testing-library/react'
 import { AbcFrame } from './abc-frame'
-import { mockI18n } from '../../test-utils/mock-i18n'
+import { mockI18n } from '../../../components/markdown-renderer/test-utils/mock-i18n'
 
 describe('AbcFrame', () => {
   afterEach(() => {
     jest.resetModules()
     jest.restoreAllMocks()
   })
-  beforeEach(async () => {
-    await mockI18n()
-  })
+  beforeEach(() => mockI18n())
 
   it('renders a music sheet', async () => {
     const element = (
diff --git a/src/components/markdown-renderer/markdown-extension/abcjs/abc-frame.tsx b/src/extensions/extra-integrations/abcjs/abc-frame.tsx
similarity index 74%
rename from src/components/markdown-renderer/markdown-extension/abcjs/abc-frame.tsx
rename to src/extensions/extra-integrations/abcjs/abc-frame.tsx
index 92a387c1a..ee59d70db 100644
--- a/src/components/markdown-renderer/markdown-extension/abcjs/abc-frame.tsx
+++ b/src/extensions/extra-integrations/abcjs/abc-frame.tsx
@@ -6,16 +6,16 @@
 
 import React, { useRef } from 'react'
 import styles from './abc.module.scss'
-import { Logger } from '../../../../utils/logger'
-import type { CodeProps } from '../../replace-components/code-block-component-replacer'
-import { cypressId } from '../../../../utils/cypress-attribute'
 import { useAsync } from 'react-use'
-import { AsyncLoadingBoundary } from '../../../common/async-loading-boundary'
-import { WaitSpinner } from '../../../common/wait-spinner/wait-spinner'
-import { useEffectWithCatch } from '../../../../hooks/common/use-effect-with-catch'
 import { Alert } from 'react-bootstrap'
-import { ShowIf } from '../../../common/show-if/show-if'
 import { Trans } from 'react-i18next'
+import { WaitSpinner } from '../../../components/common/wait-spinner/wait-spinner'
+import type { CodeProps } from '../../../components/markdown-renderer/replace-components/code-block-component-replacer'
+import { cypressId } from '../../../utils/cypress-attribute'
+import { AsyncLoadingBoundary } from '../../../components/common/async-loading-boundary'
+import { ShowIf } from '../../../components/common/show-if/show-if'
+import { useEffectWithCatch } from '../../../hooks/common/use-effect-with-catch'
+import { Logger } from '../../../utils/logger'
 
 const log = new Logger('AbcFrame')
 
diff --git a/src/components/markdown-renderer/markdown-extension/abcjs/abc.module.scss b/src/extensions/extra-integrations/abcjs/abc.module.scss
similarity index 66%
rename from src/components/markdown-renderer/markdown-extension/abcjs/abc.module.scss
rename to src/extensions/extra-integrations/abcjs/abc.module.scss
index 249e055f3..2b9295b29 100644
--- a/src/components/markdown-renderer/markdown-extension/abcjs/abc.module.scss
+++ b/src/extensions/extra-integrations/abcjs/abc.module.scss
@@ -1,5 +1,5 @@
-/*
- * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+/*!
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
  *
  * SPDX-License-Identifier: AGPL-3.0-only
  */
@@ -15,7 +15,7 @@
   }
 
   &, text {
-    @import "../../../../../global-styles/variables.module";
+    @import "../../../../global-styles/variables.module";
     font-family: $font-family-base;
   }
 }
diff --git a/src/extensions/extra-integrations/abcjs/abcjs-app-extension.ts b/src/extensions/extra-integrations/abcjs/abcjs-app-extension.ts
new file mode 100644
index 000000000..d2bbdf1a0
--- /dev/null
+++ b/src/extensions/extra-integrations/abcjs/abcjs-app-extension.ts
@@ -0,0 +1,15 @@
+/*
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import { AppExtension } from '../../base/app-extension'
+import { AbcjsMarkdownExtension } from './abcjs-markdown-extension'
+import type { MarkdownRendererExtension } from '../../../components/markdown-renderer/extensions/base/markdown-renderer-extension'
+
+export class AbcjsAppExtension extends AppExtension {
+  buildMarkdownRendererExtensions(): MarkdownRendererExtension[] {
+    return [new AbcjsMarkdownExtension()]
+  }
+}
diff --git a/src/components/markdown-renderer/markdown-extension/abcjs/abcjs-markdown-extension.test.tsx b/src/extensions/extra-integrations/abcjs/abcjs-markdown-extension.test.tsx
similarity index 79%
rename from src/components/markdown-renderer/markdown-extension/abcjs/abcjs-markdown-extension.test.tsx
rename to src/extensions/extra-integrations/abcjs/abcjs-markdown-extension.test.tsx
index 92f4e2103..2c67f46d1 100644
--- a/src/components/markdown-renderer/markdown-extension/abcjs/abcjs-markdown-extension.test.tsx
+++ b/src/extensions/extra-integrations/abcjs/abcjs-markdown-extension.test.tsx
@@ -6,11 +6,11 @@
 
 import React from 'react'
 import { render } from '@testing-library/react'
-import { TestMarkdownRenderer } from '../../test-utils/test-markdown-renderer'
 import * as AbcFrameModule from './abc-frame'
-import type { CodeProps } from '../../replace-components/code-block-component-replacer'
 import { AbcjsMarkdownExtension } from './abcjs-markdown-extension'
-import { mockI18n } from '../../test-utils/mock-i18n'
+import { mockI18n } from '../../../components/markdown-renderer/test-utils/mock-i18n'
+import type { CodeProps } from '../../../components/markdown-renderer/replace-components/code-block-component-replacer'
+import { TestMarkdownRenderer } from '../../../components/markdown-renderer/test-utils/test-markdown-renderer'
 
 jest.mock('./abc-frame')
 
diff --git a/src/extensions/extra-integrations/abcjs/abcjs-markdown-extension.ts b/src/extensions/extra-integrations/abcjs/abcjs-markdown-extension.ts
new file mode 100644
index 000000000..1ea19f747
--- /dev/null
+++ b/src/extensions/extra-integrations/abcjs/abcjs-markdown-extension.ts
@@ -0,0 +1,18 @@
+/*
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import { AbcFrame } from './abc-frame'
+import { CodeBlockMarkdownRendererExtension } from '../../../components/markdown-renderer/extensions/base/code-block-markdown-extension/code-block-markdown-renderer-extension'
+import { CodeBlockComponentReplacer } from '../../../components/markdown-renderer/replace-components/code-block-component-replacer'
+
+/**
+ * Adds support for abc.js to the markdown rendering using code fences with "abc" as language.
+ */
+export class AbcjsMarkdownExtension extends CodeBlockMarkdownRendererExtension {
+  public buildReplacers(): CodeBlockComponentReplacer[] {
+    return [new CodeBlockComponentReplacer(AbcFrame, 'abc')]
+  }
+}
diff --git a/src/extensions/extra-integrations/alert/alert-app-extension.ts b/src/extensions/extra-integrations/alert/alert-app-extension.ts
new file mode 100644
index 000000000..aaf51bf50
--- /dev/null
+++ b/src/extensions/extra-integrations/alert/alert-app-extension.ts
@@ -0,0 +1,18 @@
+/*
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import { AppExtension } from '../../base/app-extension'
+import { AlertMarkdownExtension } from './alert-markdown-extension'
+import type { MarkdownRendererExtension } from '../../../components/markdown-renderer/extensions/base/markdown-renderer-extension'
+
+/**
+ * Adds alert boxes to the markdown rendering.
+ */
+export class AlertAppExtension extends AppExtension {
+  buildMarkdownRendererExtensions(): MarkdownRendererExtension[] {
+    return [new AlertMarkdownExtension()]
+  }
+}
diff --git a/src/components/markdown-renderer/markdown-extension/alert-markdown-extension.ts b/src/extensions/extra-integrations/alert/alert-markdown-extension.ts
similarity index 82%
rename from src/components/markdown-renderer/markdown-extension/alert-markdown-extension.ts
rename to src/extensions/extra-integrations/alert/alert-markdown-extension.ts
index 7badbc334..2f158f9c1 100644
--- a/src/components/markdown-renderer/markdown-extension/alert-markdown-extension.ts
+++ b/src/extensions/extra-integrations/alert/alert-markdown-extension.ts
@@ -4,18 +4,18 @@
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
-import { MarkdownExtension } from './markdown-extension'
 import type MarkdownIt from 'markdown-it'
 import markdownItContainer from 'markdown-it-container'
 import type Token from 'markdown-it/lib/token'
 import type Renderer from 'markdown-it/lib/renderer'
+import { MarkdownRendererExtension } from '../../../components/markdown-renderer/extensions/base/markdown-renderer-extension'
 
 export const alertLevels = ['success', 'danger', 'info', 'warning']
 
 /**
  * Adds alert boxes to the markdown rendering.
  */
-export class AlertMarkdownExtension extends MarkdownExtension {
+export class AlertMarkdownExtension extends MarkdownRendererExtension {
   public configureMarkdownIt(markdownIt: MarkdownIt): void {
     alertLevels.forEach((level) => {
       markdownItContainer(markdownIt, level, {
diff --git a/src/extensions/extra-integrations/blockquote/blockquote-app-extension.ts b/src/extensions/extra-integrations/blockquote/blockquote-app-extension.ts
new file mode 100644
index 000000000..44fe10d6c
--- /dev/null
+++ b/src/extensions/extra-integrations/blockquote/blockquote-app-extension.ts
@@ -0,0 +1,18 @@
+/*
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import { AppExtension } from '../../base/app-extension'
+import type { MarkdownRendererExtension } from '../../../components/markdown-renderer/extensions/base/markdown-renderer-extension'
+import { BlockquoteExtraTagMarkdownExtension } from './blockquote-extra-tag-markdown-extension'
+
+/**
+ * Adds support for generic blockquote extra tags and blockquote color extra tags.
+ */
+export class BlockquoteAppExtension extends AppExtension {
+  buildMarkdownRendererExtensions(): MarkdownRendererExtension[] {
+    return [new BlockquoteExtraTagMarkdownExtension()]
+  }
+}
diff --git a/src/components/markdown-renderer/markdown-extension/blockquote/blockquote-border-color-node-preprocessor.ts b/src/extensions/extra-integrations/blockquote/blockquote-border-color-node-preprocessor.ts
similarity index 97%
rename from src/components/markdown-renderer/markdown-extension/blockquote/blockquote-border-color-node-preprocessor.ts
rename to src/extensions/extra-integrations/blockquote/blockquote-border-color-node-preprocessor.ts
index a9987bd42..649cbe4ad 100644
--- a/src/components/markdown-renderer/markdown-extension/blockquote/blockquote-border-color-node-preprocessor.ts
+++ b/src/extensions/extra-integrations/blockquote/blockquote-border-color-node-preprocessor.ts
@@ -6,9 +6,9 @@
 
 import type { Element, Node } from 'domhandler'
 import { isTag, isText } from 'domhandler'
-import { TravelerNodeProcessor } from '../../node-preprocessors/traveler-node-processor'
 import { Optional } from '@mrdrogdrog/optional'
 import { BlockquoteExtraTagMarkdownExtension } from './blockquote-extra-tag-markdown-extension'
+import { TravelerNodeProcessor } from '../../../components/markdown-renderer/node-preprocessors/traveler-node-processor'
 
 /**
  * Detects blockquotes with blockquote color tags and uses them to color the blockquote border.
diff --git a/src/components/markdown-renderer/markdown-extension/blockquote/blockquote-color-extra-tag-replacer.tsx b/src/extensions/extra-integrations/blockquote/blockquote-color-extra-tag-replacer.tsx
similarity index 79%
rename from src/components/markdown-renderer/markdown-extension/blockquote/blockquote-color-extra-tag-replacer.tsx
rename to src/extensions/extra-integrations/blockquote/blockquote-color-extra-tag-replacer.tsx
index 289578883..0edc048f9 100644
--- a/src/components/markdown-renderer/markdown-extension/blockquote/blockquote-color-extra-tag-replacer.tsx
+++ b/src/extensions/extra-integrations/blockquote/blockquote-color-extra-tag-replacer.tsx
@@ -4,15 +4,18 @@
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
-import type { NodeReplacement } from '../../replace-components/component-replacer'
-import { ComponentReplacer, DO_NOT_REPLACE } from '../../replace-components/component-replacer'
 import type { Element } from 'domhandler'
 import { isText } from 'domhandler'
-import { ForkAwesomeIcon } from '../../../common/fork-awesome/fork-awesome-icon'
 import { cssColor } from './blockquote-border-color-node-preprocessor'
 import type { Text } from 'domhandler/lib/node'
 import { BlockquoteExtraTagMarkdownExtension } from './blockquote-extra-tag-markdown-extension'
 import { Optional } from '@mrdrogdrog/optional'
+import type { NodeReplacement } from '../../../components/markdown-renderer/replace-components/component-replacer'
+import {
+  ComponentReplacer,
+  DO_NOT_REPLACE
+} from '../../../components/markdown-renderer/replace-components/component-replacer'
+import { ForkAwesomeIcon } from '../../../components/common/fork-awesome/fork-awesome-icon'
 
 /**
  * Replaces <blockquote-tag> elements with "color" as label and a valid color as content
diff --git a/src/components/markdown-renderer/markdown-extension/blockquote/blockquote-extra-tag-markdown-extension.ts b/src/extensions/extra-integrations/blockquote/blockquote-extra-tag-markdown-extension.ts
similarity index 79%
rename from src/components/markdown-renderer/markdown-extension/blockquote/blockquote-extra-tag-markdown-extension.ts
rename to src/extensions/extra-integrations/blockquote/blockquote-extra-tag-markdown-extension.ts
index b404e2cd9..b6f1f6dec 100644
--- a/src/components/markdown-renderer/markdown-extension/blockquote/blockquote-extra-tag-markdown-extension.ts
+++ b/src/extensions/extra-integrations/blockquote/blockquote-extra-tag-markdown-extension.ts
@@ -4,19 +4,19 @@
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
-import { MarkdownExtension } from '../markdown-extension'
 import { BlockquoteColorExtraTagReplacer } from './blockquote-color-extra-tag-replacer'
 import { BlockquoteExtraTagReplacer } from './blockquote-extra-tag-replacer'
-import type { ComponentReplacer } from '../../replace-components/component-replacer'
 import type MarkdownIt from 'markdown-it'
-import type { NodeProcessor } from '../../node-preprocessors/node-processor'
 import { BlockquoteBorderColorNodePreprocessor } from './blockquote-border-color-node-preprocessor'
 import { BlockquoteExtraTagMarkdownItPlugin } from './blockquote-extra-tag-markdown-it-plugin'
+import type { NodeProcessor } from '../../../components/markdown-renderer/node-preprocessors/node-processor'
+import type { ComponentReplacer } from '../../../components/markdown-renderer/replace-components/component-replacer'
+import { MarkdownRendererExtension } from '../../../components/markdown-renderer/extensions/base/markdown-renderer-extension'
 
 /**
  * Adds support for generic blockquote extra tags and blockquote color extra tags.
  */
-export class BlockquoteExtraTagMarkdownExtension extends MarkdownExtension {
+export class BlockquoteExtraTagMarkdownExtension extends MarkdownRendererExtension {
   public static readonly tagName = 'app-blockquote-tag'
 
   public configureMarkdownIt(markdownIt: MarkdownIt): void {
diff --git a/src/components/markdown-renderer/markdown-extension/blockquote/blockquote-extra-tag-markdown-it-plugin.test.ts b/src/extensions/extra-integrations/blockquote/blockquote-extra-tag-markdown-it-plugin.test.ts
similarity index 95%
rename from src/components/markdown-renderer/markdown-extension/blockquote/blockquote-extra-tag-markdown-it-plugin.test.ts
rename to src/extensions/extra-integrations/blockquote/blockquote-extra-tag-markdown-it-plugin.test.ts
index 149d9983f..8a77270ff 100644
--- a/src/components/markdown-renderer/markdown-extension/blockquote/blockquote-extra-tag-markdown-it-plugin.test.ts
+++ b/src/extensions/extra-integrations/blockquote/blockquote-extra-tag-markdown-it-plugin.test.ts
@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
  *
  * SPDX-License-Identifier: AGPL-3.0-only
  */
diff --git a/src/components/markdown-renderer/markdown-extension/blockquote/blockquote-extra-tag-markdown-it-plugin.ts b/src/extensions/extra-integrations/blockquote/blockquote-extra-tag-markdown-it-plugin.ts
similarity index 98%
rename from src/components/markdown-renderer/markdown-extension/blockquote/blockquote-extra-tag-markdown-it-plugin.ts
rename to src/extensions/extra-integrations/blockquote/blockquote-extra-tag-markdown-it-plugin.ts
index cbcc63b55..c2e26b0c0 100644
--- a/src/components/markdown-renderer/markdown-extension/blockquote/blockquote-extra-tag-markdown-it-plugin.ts
+++ b/src/extensions/extra-integrations/blockquote/blockquote-extra-tag-markdown-it-plugin.ts
@@ -6,11 +6,11 @@
 
 import type MarkdownIt from 'markdown-it/lib'
 import type Token from 'markdown-it/lib/token'
-import type { IconName } from '../../../common/fork-awesome/types'
 import { Optional } from '@mrdrogdrog/optional'
 import type StateInline from 'markdown-it/lib/rules_inline/state_inline'
 import { BlockquoteExtraTagMarkdownExtension } from './blockquote-extra-tag-markdown-extension'
 import type { RuleInline } from 'markdown-it/lib/parser_inline'
+import type { IconName } from '../../../components/common/fork-awesome/types'
 
 export interface BlockquoteTagOptions {
   parseSubTags?: boolean
diff --git a/src/components/markdown-renderer/markdown-extension/blockquote/blockquote-extra-tag-replacer.tsx b/src/extensions/extra-integrations/blockquote/blockquote-extra-tag-replacer.tsx
similarity index 73%
rename from src/components/markdown-renderer/markdown-extension/blockquote/blockquote-extra-tag-replacer.tsx
rename to src/extensions/extra-integrations/blockquote/blockquote-extra-tag-replacer.tsx
index 888e31ea0..ce5db804b 100644
--- a/src/components/markdown-renderer/markdown-extension/blockquote/blockquote-extra-tag-replacer.tsx
+++ b/src/extensions/extra-integrations/blockquote/blockquote-extra-tag-replacer.tsx
@@ -4,16 +4,22 @@
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
-import type { NodeReplacement, SubNodeTransform } from '../../replace-components/component-replacer'
-import { ComponentReplacer, DO_NOT_REPLACE } from '../../replace-components/component-replacer'
 import type { Element } from 'domhandler'
-import type { ForkAwesomeIconProps } from '../../../common/fork-awesome/fork-awesome-icon'
-import { ForkAwesomeIcon } from '../../../common/fork-awesome/fork-awesome-icon'
-import type { IconName } from '../../../common/fork-awesome/types'
-import { ForkAwesomeIcons } from '../../../common/fork-awesome/fork-awesome-icons'
 import { Optional } from '@mrdrogdrog/optional'
 import type { ReactElement } from 'react'
 import { BlockquoteExtraTagMarkdownExtension } from './blockquote-extra-tag-markdown-extension'
+import type {
+  NodeReplacement,
+  SubNodeTransform
+} from '../../../components/markdown-renderer/replace-components/component-replacer'
+import {
+  ComponentReplacer,
+  DO_NOT_REPLACE
+} from '../../../components/markdown-renderer/replace-components/component-replacer'
+import { ForkAwesomeIcons } from '../../../components/common/fork-awesome/fork-awesome-icons'
+import type { ForkAwesomeIconProps } from '../../../components/common/fork-awesome/fork-awesome-icon'
+import { ForkAwesomeIcon } from '../../../components/common/fork-awesome/fork-awesome-icon'
+import type { IconName } from '../../../components/common/fork-awesome/types'
 
 /**
  * Replaces <blockquote-tag> elements with an icon and a small text.
diff --git a/src/components/markdown-renderer/markdown-extension/csv/__snapshots__/csv-table-markdown-extension.test.tsx.snap b/src/extensions/extra-integrations/csv/__snapshots__/csv-table-markdown-extension.test.tsx.snap
similarity index 100%
rename from src/components/markdown-renderer/markdown-extension/csv/__snapshots__/csv-table-markdown-extension.test.tsx.snap
rename to src/extensions/extra-integrations/csv/__snapshots__/csv-table-markdown-extension.test.tsx.snap
diff --git a/src/components/markdown-renderer/markdown-extension/csv/__snapshots__/csv-table.test.tsx.snap b/src/extensions/extra-integrations/csv/__snapshots__/csv-table.test.tsx.snap
similarity index 100%
rename from src/components/markdown-renderer/markdown-extension/csv/__snapshots__/csv-table.test.tsx.snap
rename to src/extensions/extra-integrations/csv/__snapshots__/csv-table.test.tsx.snap
diff --git a/src/components/markdown-renderer/markdown-extension/csv/csv-parser.test.ts b/src/extensions/extra-integrations/csv/csv-parser.test.ts
similarity index 92%
rename from src/components/markdown-renderer/markdown-extension/csv/csv-parser.test.ts
rename to src/extensions/extra-integrations/csv/csv-parser.test.ts
index 3273daeab..21d678437 100644
--- a/src/components/markdown-renderer/markdown-extension/csv/csv-parser.test.ts
+++ b/src/extensions/extra-integrations/csv/csv-parser.test.ts
@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
  *
  * SPDX-License-Identifier: AGPL-3.0-only
  */
diff --git a/src/components/markdown-renderer/markdown-extension/csv/csv-parser.ts b/src/extensions/extra-integrations/csv/csv-parser.ts
similarity index 100%
rename from src/components/markdown-renderer/markdown-extension/csv/csv-parser.ts
rename to src/extensions/extra-integrations/csv/csv-parser.ts
diff --git a/src/components/markdown-renderer/markdown-extension/csv/csv-replacer.tsx b/src/extensions/extra-integrations/csv/csv-replacer.tsx
similarity index 70%
rename from src/components/markdown-renderer/markdown-extension/csv/csv-replacer.tsx
rename to src/extensions/extra-integrations/csv/csv-replacer.tsx
index 233fbf287..df4ada86c 100644
--- a/src/components/markdown-renderer/markdown-extension/csv/csv-replacer.tsx
+++ b/src/extensions/extra-integrations/csv/csv-replacer.tsx
@@ -6,10 +6,13 @@
 
 import type { Element } from 'domhandler'
 import React from 'react'
-import type { NodeReplacement } from '../../replace-components/component-replacer'
-import { ComponentReplacer, DO_NOT_REPLACE } from '../../replace-components/component-replacer'
+import type { NodeReplacement } from '../../../components/markdown-renderer/replace-components/component-replacer'
 import { CsvTable } from './csv-table'
-import { CodeBlockComponentReplacer } from '../../replace-components/code-block-component-replacer'
+import {
+  ComponentReplacer,
+  DO_NOT_REPLACE
+} from '../../../components/markdown-renderer/replace-components/component-replacer'
+import { CodeBlockComponentReplacer } from '../../../components/markdown-renderer/replace-components/code-block-component-replacer'
 
 /**
  * Detects code blocks with "csv" as language and renders them as table.
diff --git a/src/extensions/extra-integrations/csv/csv-table-app-extension.ts b/src/extensions/extra-integrations/csv/csv-table-app-extension.ts
new file mode 100644
index 000000000..0eaf2befe
--- /dev/null
+++ b/src/extensions/extra-integrations/csv/csv-table-app-extension.ts
@@ -0,0 +1,18 @@
+/*
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import { AppExtension } from '../../base/app-extension'
+import type { MarkdownRendererExtension } from '../../../components/markdown-renderer/extensions/base/markdown-renderer-extension'
+import { CsvTableMarkdownExtension } from './csv-table-markdown-extension'
+
+/**
+ * Adds support for csv tables to the markdown rendering.
+ */
+export class CsvTableAppExtension extends AppExtension {
+  buildMarkdownRendererExtensions(): MarkdownRendererExtension[] {
+    return [new CsvTableMarkdownExtension()]
+  }
+}
diff --git a/src/components/markdown-renderer/markdown-extension/csv/csv-table-markdown-extension.test.tsx b/src/extensions/extra-integrations/csv/csv-table-markdown-extension.test.tsx
similarity index 76%
rename from src/components/markdown-renderer/markdown-extension/csv/csv-table-markdown-extension.test.tsx
rename to src/extensions/extra-integrations/csv/csv-table-markdown-extension.test.tsx
index eb624bb3b..1875c2c7e 100644
--- a/src/components/markdown-renderer/markdown-extension/csv/csv-table-markdown-extension.test.tsx
+++ b/src/extensions/extra-integrations/csv/csv-table-markdown-extension.test.tsx
@@ -6,11 +6,11 @@
 
 import * as CsvTableModule from '../csv/csv-table'
 import React from 'react'
-import type { CodeProps } from '../../replace-components/code-block-component-replacer'
-import { mockI18n } from '../../test-utils/mock-i18n'
 import { render } from '@testing-library/react'
-import { TestMarkdownRenderer } from '../../test-utils/test-markdown-renderer'
 import { CsvTableMarkdownExtension } from './csv-table-markdown-extension'
+import { mockI18n } from '../../../components/markdown-renderer/test-utils/mock-i18n'
+import type { CodeProps } from '../../../components/markdown-renderer/replace-components/code-block-component-replacer'
+import { TestMarkdownRenderer } from '../../../components/markdown-renderer/test-utils/test-markdown-renderer'
 
 jest.mock('../csv/csv-table')
 
diff --git a/src/extensions/extra-integrations/csv/csv-table-markdown-extension.ts b/src/extensions/extra-integrations/csv/csv-table-markdown-extension.ts
new file mode 100644
index 000000000..188781329
--- /dev/null
+++ b/src/extensions/extra-integrations/csv/csv-table-markdown-extension.ts
@@ -0,0 +1,18 @@
+/*
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import { CsvReplacer } from './csv-replacer'
+import { MarkdownRendererExtension } from '../../../components/markdown-renderer/extensions/base/markdown-renderer-extension'
+import type { ComponentReplacer } from '../../../components/markdown-renderer/replace-components/component-replacer'
+
+/**
+ * Adds support for csv tables to the markdown rendering using code fences with "csv" as language.
+ */
+export class CsvTableMarkdownExtension extends MarkdownRendererExtension {
+  public buildReplacers(): ComponentReplacer[] {
+    return [new CsvReplacer()]
+  }
+}
diff --git a/src/components/markdown-renderer/markdown-extension/csv/csv-table.test.tsx b/src/extensions/extra-integrations/csv/csv-table.test.tsx
similarity index 100%
rename from src/components/markdown-renderer/markdown-extension/csv/csv-table.test.tsx
rename to src/extensions/extra-integrations/csv/csv-table.test.tsx
diff --git a/src/components/markdown-renderer/markdown-extension/csv/csv-table.tsx b/src/extensions/extra-integrations/csv/csv-table.tsx
similarity index 96%
rename from src/components/markdown-renderer/markdown-extension/csv/csv-table.tsx
rename to src/extensions/extra-integrations/csv/csv-table.tsx
index 9d3e0f31f..3c776aa38 100644
--- a/src/components/markdown-renderer/markdown-extension/csv/csv-table.tsx
+++ b/src/extensions/extra-integrations/csv/csv-table.tsx
@@ -6,7 +6,7 @@
 
 import React, { useMemo } from 'react'
 import { parseCsv } from './csv-parser'
-import { cypressId } from '../../../../utils/cypress-attribute'
+import { cypressId } from '../../../utils/cypress-attribute'
 
 export interface CsvTableProps {
   code: string
diff --git a/src/components/markdown-renderer/markdown-extension/flowchart/__snapshots__/flowchart-markdown-extension.test.tsx.snap b/src/extensions/extra-integrations/flowchart/__snapshots__/flowchart-markdown-extension.test.tsx.snap
similarity index 100%
rename from src/components/markdown-renderer/markdown-extension/flowchart/__snapshots__/flowchart-markdown-extension.test.tsx.snap
rename to src/extensions/extra-integrations/flowchart/__snapshots__/flowchart-markdown-extension.test.tsx.snap
diff --git a/src/components/markdown-renderer/markdown-extension/flowchart/__snapshots__/flowchart.test.tsx.snap b/src/extensions/extra-integrations/flowchart/__snapshots__/flowchart.test.tsx.snap
similarity index 100%
rename from src/components/markdown-renderer/markdown-extension/flowchart/__snapshots__/flowchart.test.tsx.snap
rename to src/extensions/extra-integrations/flowchart/__snapshots__/flowchart.test.tsx.snap
diff --git a/src/extensions/extra-integrations/flowchart/flowchart-app-extension.ts b/src/extensions/extra-integrations/flowchart/flowchart-app-extension.ts
new file mode 100644
index 000000000..c8d926469
--- /dev/null
+++ b/src/extensions/extra-integrations/flowchart/flowchart-app-extension.ts
@@ -0,0 +1,18 @@
+/*
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import { AppExtension } from '../../base/app-extension'
+import type { MarkdownRendererExtension } from '../../../components/markdown-renderer/extensions/base/markdown-renderer-extension'
+import { FlowchartMarkdownExtension } from './flowchart-markdown-extension'
+
+/**
+ * Adds support for flow charts to the markdown rendering.
+ */
+export class FlowchartAppExtension extends AppExtension {
+  buildMarkdownRendererExtensions(): MarkdownRendererExtension[] {
+    return [new FlowchartMarkdownExtension()]
+  }
+}
diff --git a/src/components/markdown-renderer/markdown-extension/flowchart/flowchart-markdown-extension.test.tsx b/src/extensions/extra-integrations/flowchart/flowchart-markdown-extension.test.tsx
similarity index 77%
rename from src/components/markdown-renderer/markdown-extension/flowchart/flowchart-markdown-extension.test.tsx
rename to src/extensions/extra-integrations/flowchart/flowchart-markdown-extension.test.tsx
index 9ac424203..90b6915b9 100644
--- a/src/components/markdown-renderer/markdown-extension/flowchart/flowchart-markdown-extension.test.tsx
+++ b/src/extensions/extra-integrations/flowchart/flowchart-markdown-extension.test.tsx
@@ -5,12 +5,12 @@
  */
 
 import { render } from '@testing-library/react'
-import { TestMarkdownRenderer } from '../../test-utils/test-markdown-renderer'
 import React from 'react'
-import { mockI18n } from '../../test-utils/mock-i18n'
 import { FlowchartMarkdownExtension } from './flowchart-markdown-extension'
 import * as Flowchart from '../flowchart/flowchart'
-import type { CodeProps } from '../../replace-components/code-block-component-replacer'
+import { mockI18n } from '../../../components/markdown-renderer/test-utils/mock-i18n'
+import type { CodeProps } from '../../../components/markdown-renderer/replace-components/code-block-component-replacer'
+import { TestMarkdownRenderer } from '../../../components/markdown-renderer/test-utils/test-markdown-renderer'
 
 jest.mock('../flowchart/flowchart')
 
diff --git a/src/extensions/extra-integrations/flowchart/flowchart-markdown-extension.ts b/src/extensions/extra-integrations/flowchart/flowchart-markdown-extension.ts
new file mode 100644
index 000000000..420d4f1d0
--- /dev/null
+++ b/src/extensions/extra-integrations/flowchart/flowchart-markdown-extension.ts
@@ -0,0 +1,18 @@
+/*
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import { FlowChart } from './flowchart'
+import { CodeBlockMarkdownRendererExtension } from '../../../components/markdown-renderer/extensions/base/code-block-markdown-extension/code-block-markdown-renderer-extension'
+import { CodeBlockComponentReplacer } from '../../../components/markdown-renderer/replace-components/code-block-component-replacer'
+
+/**
+ * Adds support for flow charts to the markdown rendering using code fences with "flow" as language.
+ */
+export class FlowchartMarkdownExtension extends CodeBlockMarkdownRendererExtension {
+  public buildReplacers(): CodeBlockComponentReplacer[] {
+    return [new CodeBlockComponentReplacer(FlowChart, 'flow')]
+  }
+}
diff --git a/src/components/markdown-renderer/markdown-extension/flowchart/flowchart.test.tsx b/src/extensions/extra-integrations/flowchart/flowchart.test.tsx
similarity index 92%
rename from src/components/markdown-renderer/markdown-extension/flowchart/flowchart.test.tsx
rename to src/extensions/extra-integrations/flowchart/flowchart.test.tsx
index dec918b6f..a2e1b1fdc 100644
--- a/src/components/markdown-renderer/markdown-extension/flowchart/flowchart.test.tsx
+++ b/src/extensions/extra-integrations/flowchart/flowchart.test.tsx
@@ -4,19 +4,17 @@
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
-import { mockI18n } from '../../test-utils/mock-i18n'
 import { render, screen } from '@testing-library/react'
 import { FlowChart } from './flowchart'
 import type * as flowchartJsModule from 'flowchart.js'
-import { StoreProvider } from '../../../../redux/store-provider'
+import { mockI18n } from '../../../components/markdown-renderer/test-utils/mock-i18n'
+import { StoreProvider } from '../../../redux/store-provider'
 
 describe('Flowchart', () => {
   const successText = 'Flowchart rendering succeeded!'
   const expectedValidFlowchartCode = 'test code'
 
-  beforeAll(async () => {
-    await mockI18n()
-  })
+  beforeAll(() => mockI18n())
 
   afterEach(() => {
     jest.resetModules()
diff --git a/src/components/markdown-renderer/markdown-extension/flowchart/flowchart.tsx b/src/extensions/extra-integrations/flowchart/flowchart.tsx
similarity index 81%
rename from src/components/markdown-renderer/markdown-extension/flowchart/flowchart.tsx
rename to src/extensions/extra-integrations/flowchart/flowchart.tsx
index 52ddb13e5..8c34c0a4c 100644
--- a/src/components/markdown-renderer/markdown-extension/flowchart/flowchart.tsx
+++ b/src/extensions/extra-integrations/flowchart/flowchart.tsx
@@ -7,14 +7,14 @@
 import React, { useEffect, useRef, useState } from 'react'
 import { Alert } from 'react-bootstrap'
 import { Trans, useTranslation } from 'react-i18next'
-import { useIsDarkModeActivated } from '../../../../hooks/common/use-is-dark-mode-activated'
-import { Logger } from '../../../../utils/logger'
-import fontStyles from '../../../../../global-styles/variables.module.scss'
+import fontStyles from '../../../../global-styles/variables.module.scss'
 import { useAsync } from 'react-use'
-import { AsyncLoadingBoundary } from '../../../common/async-loading-boundary'
-import { ShowIf } from '../../../common/show-if/show-if'
-import type { CodeProps } from '../../replace-components/code-block-component-replacer'
-import { testId } from '../../../../utils/test-id'
+import type { CodeProps } from '../../../components/markdown-renderer/replace-components/code-block-component-replacer'
+import { AsyncLoadingBoundary } from '../../../components/common/async-loading-boundary'
+import { ShowIf } from '../../../components/common/show-if/show-if'
+import { testId } from '../../../utils/test-id'
+import { useIsDarkModeActivated } from '../../../hooks/common/use-is-dark-mode-activated'
+import { Logger } from '../../../utils/logger'
 
 const log = new Logger('FlowChart')
 
diff --git a/src/extensions/extra-integrations/gist/gist-app-extension.ts b/src/extensions/extra-integrations/gist/gist-app-extension.ts
new file mode 100644
index 000000000..70eccde53
--- /dev/null
+++ b/src/extensions/extra-integrations/gist/gist-app-extension.ts
@@ -0,0 +1,18 @@
+/*
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import { AppExtension } from '../../base/app-extension'
+import type { MarkdownRendererExtension } from '../../../components/markdown-renderer/extensions/base/markdown-renderer-extension'
+import { GistMarkdownExtension } from './gist-markdown-extension'
+
+/**
+ * Adds support for embeddings of GitHub Gists to the markdown renderer.
+ */
+export class GistAppExtension extends AppExtension {
+  buildMarkdownRendererExtensions(): MarkdownRendererExtension[] {
+    return [new GistMarkdownExtension()]
+  }
+}
diff --git a/src/components/markdown-renderer/markdown-extension/gist/gist-frame.module.scss b/src/extensions/extra-integrations/gist/gist-frame.module.scss
similarity index 81%
rename from src/components/markdown-renderer/markdown-extension/gist/gist-frame.module.scss
rename to src/extensions/extra-integrations/gist/gist-frame.module.scss
index 30e0dec5b..8f62e757a 100644
--- a/src/components/markdown-renderer/markdown-extension/gist/gist-frame.module.scss
+++ b/src/extensions/extra-integrations/gist/gist-frame.module.scss
@@ -1,5 +1,5 @@
-/*
- * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+/*!
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
  *
  * SPDX-License-Identifier: AGPL-3.0-only
  */
diff --git a/src/components/markdown-renderer/markdown-extension/gist/gist-frame.tsx b/src/extensions/extra-integrations/gist/gist-frame.tsx
similarity index 77%
rename from src/components/markdown-renderer/markdown-extension/gist/gist-frame.tsx
rename to src/extensions/extra-integrations/gist/gist-frame.tsx
index f5282c1f9..c8954bb96 100644
--- a/src/components/markdown-renderer/markdown-extension/gist/gist-frame.tsx
+++ b/src/extensions/extra-integrations/gist/gist-frame.tsx
@@ -1,15 +1,15 @@
 /*
- * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
  *
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
 import React, { useCallback } from 'react'
-import { cypressId } from '../../../../utils/cypress-attribute'
 import styles from './gist-frame.module.scss'
 import { useResizeGistFrame } from './use-resize-gist-frame'
-import type { IdProps } from '../../replace-components/custom-tag-with-id-component-replacer'
-import { ClickShield } from '../../replace-components/click-shield/click-shield'
+import type { IdProps } from '../../../components/markdown-renderer/replace-components/custom-tag-with-id-component-replacer'
+import { cypressId } from '../../../utils/cypress-attribute'
+import { ClickShield } from '../../../components/markdown-renderer/replace-components/click-shield/click-shield'
 
 /**
  * This component renders a GitHub Gist by placing the gist URL in an {@link HTMLIFrameElement iframe}.
diff --git a/src/components/markdown-renderer/markdown-extension/gist/gist-markdown-extension.ts b/src/extensions/extra-integrations/gist/gist-markdown-extension.ts
similarity index 67%
rename from src/components/markdown-renderer/markdown-extension/gist/gist-markdown-extension.ts
rename to src/extensions/extra-integrations/gist/gist-markdown-extension.ts
index 56042c13a..07b044258 100644
--- a/src/components/markdown-renderer/markdown-extension/gist/gist-markdown-extension.ts
+++ b/src/extensions/extra-integrations/gist/gist-markdown-extension.ts
@@ -4,19 +4,19 @@
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
-import { MarkdownExtension } from '../markdown-extension'
 import markdownItRegex from 'markdown-it-regex'
 import type MarkdownIt from 'markdown-it'
-import type { ComponentReplacer } from '../../replace-components/component-replacer'
-import { CustomTagWithIdComponentReplacer } from '../../replace-components/custom-tag-with-id-component-replacer'
 import { replaceGistLink } from './replace-gist-link'
 import { replaceLegacyGistShortCode } from './replace-legacy-gist-short-code'
 import { GistFrame } from './gist-frame'
+import type { ComponentReplacer } from '../../../components/markdown-renderer/replace-components/component-replacer'
+import { MarkdownRendererExtension } from '../../../components/markdown-renderer/extensions/base/markdown-renderer-extension'
+import { CustomTagWithIdComponentReplacer } from '../../../components/markdown-renderer/replace-components/custom-tag-with-id-component-replacer'
 
 /**
  * Adds support for embeddings of GitHub Gists by detecting gist links and the legacy gist shortcode.
  */
-export class GistMarkdownExtension extends MarkdownExtension {
+export class GistMarkdownExtension extends MarkdownRendererExtension {
   public static readonly tagName = 'app-gist'
 
   public configureMarkdownIt(markdownIt: MarkdownIt): void {
diff --git a/src/components/markdown-renderer/markdown-extension/gist/replace-gist-link.ts b/src/extensions/extra-integrations/gist/replace-gist-link.ts
similarity index 90%
rename from src/components/markdown-renderer/markdown-extension/gist/replace-gist-link.ts
rename to src/extensions/extra-integrations/gist/replace-gist-link.ts
index 14f9eb9e4..ef1034066 100644
--- a/src/components/markdown-renderer/markdown-extension/gist/replace-gist-link.ts
+++ b/src/extensions/extra-integrations/gist/replace-gist-link.ts
@@ -4,8 +4,8 @@
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
-import type { RegexOptions } from '../../../../external-types/markdown-it-regex/interface'
 import { GistMarkdownExtension } from './gist-markdown-extension'
+import type { RegexOptions } from '../../../external-types/markdown-it-regex/interface'
 
 const protocolRegex = /(?:http(?:s)?:\/\/)?/
 const domainRegex = /(?:gist\.github\.com\/)/
diff --git a/src/components/markdown-renderer/markdown-extension/gist/replace-legacy-gist-short-code.ts b/src/extensions/extra-integrations/gist/replace-legacy-gist-short-code.ts
similarity index 88%
rename from src/components/markdown-renderer/markdown-extension/gist/replace-legacy-gist-short-code.ts
rename to src/extensions/extra-integrations/gist/replace-legacy-gist-short-code.ts
index 54bd62c03..d29b36e7a 100644
--- a/src/components/markdown-renderer/markdown-extension/gist/replace-legacy-gist-short-code.ts
+++ b/src/extensions/extra-integrations/gist/replace-legacy-gist-short-code.ts
@@ -4,8 +4,8 @@
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
-import type { RegexOptions } from '../../../../external-types/markdown-it-regex/interface'
 import { GistMarkdownExtension } from './gist-markdown-extension'
+import type { RegexOptions } from '../../../external-types/markdown-it-regex/interface'
 
 const finalRegex = /^{%gist\s+(\w+\/\w+)\s*%}$/
 
diff --git a/src/components/markdown-renderer/markdown-extension/gist/use-resize-gist-frame.ts b/src/extensions/extra-integrations/gist/use-resize-gist-frame.ts
similarity index 96%
rename from src/components/markdown-renderer/markdown-extension/gist/use-resize-gist-frame.ts
rename to src/extensions/extra-integrations/gist/use-resize-gist-frame.ts
index 77cd4bb1f..2cc7ac59a 100644
--- a/src/components/markdown-renderer/markdown-extension/gist/use-resize-gist-frame.ts
+++ b/src/extensions/extra-integrations/gist/use-resize-gist-frame.ts
@@ -6,7 +6,7 @@
 
 import type React from 'react'
 import { useCallback, useRef, useState } from 'react'
-import { useBindPointerMovementEventOnWindow } from '../../../../hooks/common/use-bind-pointer-movement-event-on-window'
+import { useBindPointerMovementEventOnWindow } from '../../../hooks/common/use-bind-pointer-movement-event-on-window'
 
 /**
  * Determines if the left mouse button is pressed in the given event
diff --git a/src/components/markdown-renderer/markdown-extension/graphviz/__snapshots__/graphviz-markdown-extension.test.tsx.snap b/src/extensions/extra-integrations/graphviz/__snapshots__/graphviz-markdown-extension.test.tsx.snap
similarity index 100%
rename from src/components/markdown-renderer/markdown-extension/graphviz/__snapshots__/graphviz-markdown-extension.test.tsx.snap
rename to src/extensions/extra-integrations/graphviz/__snapshots__/graphviz-markdown-extension.test.tsx.snap
diff --git a/src/extensions/extra-integrations/graphviz/graphviz-app-extension.ts b/src/extensions/extra-integrations/graphviz/graphviz-app-extension.ts
new file mode 100644
index 000000000..4ca5d3243
--- /dev/null
+++ b/src/extensions/extra-integrations/graphviz/graphviz-app-extension.ts
@@ -0,0 +1,18 @@
+/*
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import { AppExtension } from '../../base/app-extension'
+import type { MarkdownRendererExtension } from '../../../components/markdown-renderer/extensions/base/markdown-renderer-extension'
+import { GraphvizMarkdownExtension } from './graphviz-markdown-extension'
+
+/**
+ * Adds support for graphviz to the markdown rendering.
+ */
+export class GraphvizAppExtension extends AppExtension {
+  buildMarkdownRendererExtensions(): MarkdownRendererExtension[] {
+    return [new GraphvizMarkdownExtension()]
+  }
+}
diff --git a/src/components/markdown-renderer/markdown-extension/graphviz/graphviz-frame.tsx b/src/extensions/extra-integrations/graphviz/graphviz-frame.tsx
similarity index 87%
rename from src/components/markdown-renderer/markdown-extension/graphviz/graphviz-frame.tsx
rename to src/extensions/extra-integrations/graphviz/graphviz-frame.tsx
index 264b541ed..21fdc8622 100644
--- a/src/components/markdown-renderer/markdown-extension/graphviz/graphviz-frame.tsx
+++ b/src/extensions/extra-integrations/graphviz/graphviz-frame.tsx
@@ -6,11 +6,11 @@
 
 import React, { Fragment, useCallback, useEffect, useRef, useState } from 'react'
 import { Alert } from 'react-bootstrap'
-import { ShowIf } from '../../../common/show-if/show-if'
-import { Logger } from '../../../../utils/logger'
-import { cypressId } from '../../../../utils/cypress-attribute'
-import type { CodeProps } from '../../replace-components/code-block-component-replacer'
 import { useRouter } from 'next/router'
+import type { CodeProps } from '../../../components/markdown-renderer/replace-components/code-block-component-replacer'
+import { cypressId } from '../../../utils/cypress-attribute'
+import { ShowIf } from '../../../components/common/show-if/show-if'
+import { Logger } from '../../../utils/logger'
 
 const log = new Logger('GraphvizFrame')
 /**
diff --git a/src/components/markdown-renderer/markdown-extension/graphviz/graphviz-markdown-extension.test.tsx b/src/extensions/extra-integrations/graphviz/graphviz-markdown-extension.test.tsx
similarity index 77%
rename from src/components/markdown-renderer/markdown-extension/graphviz/graphviz-markdown-extension.test.tsx
rename to src/extensions/extra-integrations/graphviz/graphviz-markdown-extension.test.tsx
index a64dbe0dd..e753f1385 100644
--- a/src/components/markdown-renderer/markdown-extension/graphviz/graphviz-markdown-extension.test.tsx
+++ b/src/extensions/extra-integrations/graphviz/graphviz-markdown-extension.test.tsx
@@ -5,12 +5,12 @@
  */
 
 import { render } from '@testing-library/react'
-import { TestMarkdownRenderer } from '../../test-utils/test-markdown-renderer'
 import React from 'react'
-import { mockI18n } from '../../test-utils/mock-i18n'
 import { GraphvizMarkdownExtension } from './graphviz-markdown-extension'
 import * as GraphvizFrameModule from '../graphviz/graphviz-frame'
-import type { CodeProps } from '../../replace-components/code-block-component-replacer'
+import { mockI18n } from '../../../components/markdown-renderer/test-utils/mock-i18n'
+import type { CodeProps } from '../../../components/markdown-renderer/replace-components/code-block-component-replacer'
+import { TestMarkdownRenderer } from '../../../components/markdown-renderer/test-utils/test-markdown-renderer'
 
 jest.mock('../graphviz/graphviz-frame')
 
diff --git a/src/extensions/extra-integrations/graphviz/graphviz-markdown-extension.ts b/src/extensions/extra-integrations/graphviz/graphviz-markdown-extension.ts
new file mode 100644
index 000000000..c565cddc5
--- /dev/null
+++ b/src/extensions/extra-integrations/graphviz/graphviz-markdown-extension.ts
@@ -0,0 +1,18 @@
+/*
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import { GraphvizFrame } from './graphviz-frame'
+import { CodeBlockMarkdownRendererExtension } from '../../../components/markdown-renderer/extensions/base/code-block-markdown-extension/code-block-markdown-renderer-extension'
+import { CodeBlockComponentReplacer } from '../../../components/markdown-renderer/replace-components/code-block-component-replacer'
+
+/**
+ * Adds support for graphviz to the markdown rendering using code fences with "graphviz" as language.
+ */
+export class GraphvizMarkdownExtension extends CodeBlockMarkdownRendererExtension {
+  public buildReplacers(): CodeBlockComponentReplacer[] {
+    return [new CodeBlockComponentReplacer(GraphvizFrame, 'graphviz')]
+  }
+}
diff --git a/src/components/markdown-renderer/markdown-extension/highlighted-fence/__snapshots__/highlighted-code-markdown-extension.test.tsx.snap b/src/extensions/extra-integrations/highlighted-code-fence/__snapshots__/highlighted-code-markdown-extension.test.tsx.snap
similarity index 100%
rename from src/components/markdown-renderer/markdown-extension/highlighted-fence/__snapshots__/highlighted-code-markdown-extension.test.tsx.snap
rename to src/extensions/extra-integrations/highlighted-code-fence/__snapshots__/highlighted-code-markdown-extension.test.tsx.snap
diff --git a/src/components/markdown-renderer/markdown-extension/highlighted-fence/__snapshots__/highlighted-code.test.tsx.snap b/src/extensions/extra-integrations/highlighted-code-fence/__snapshots__/highlighted-code.test.tsx.snap
similarity index 100%
rename from src/components/markdown-renderer/markdown-extension/highlighted-fence/__snapshots__/highlighted-code.test.tsx.snap
rename to src/extensions/extra-integrations/highlighted-code-fence/__snapshots__/highlighted-code.test.tsx.snap
diff --git a/src/extensions/extra-integrations/highlighted-code-fence/highlighted-code-fence-app-extension.ts b/src/extensions/extra-integrations/highlighted-code-fence/highlighted-code-fence-app-extension.ts
new file mode 100644
index 000000000..37e2f8812
--- /dev/null
+++ b/src/extensions/extra-integrations/highlighted-code-fence/highlighted-code-fence-app-extension.ts
@@ -0,0 +1,18 @@
+/*
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import { AppExtension } from '../../base/app-extension'
+import type { MarkdownRendererExtension } from '../../../components/markdown-renderer/extensions/base/markdown-renderer-extension'
+import { HighlightedCodeMarkdownExtension } from './highlighted-code-markdown-extension'
+
+/**
+ * Adds code highlighting to the markdown rendering.
+ */
+export class HighlightedCodeFenceAppExtension extends AppExtension {
+  buildMarkdownRendererExtensions(): MarkdownRendererExtension[] {
+    return [new HighlightedCodeMarkdownExtension()]
+  }
+}
diff --git a/src/components/markdown-renderer/markdown-extension/highlighted-fence/highlighted-code-markdown-extension.test.tsx b/src/extensions/extra-integrations/highlighted-code-fence/highlighted-code-markdown-extension.test.tsx
similarity index 95%
rename from src/components/markdown-renderer/markdown-extension/highlighted-fence/highlighted-code-markdown-extension.test.tsx
rename to src/extensions/extra-integrations/highlighted-code-fence/highlighted-code-markdown-extension.test.tsx
index b86385baa..595c854bf 100644
--- a/src/components/markdown-renderer/markdown-extension/highlighted-fence/highlighted-code-markdown-extension.test.tsx
+++ b/src/extensions/extra-integrations/highlighted-code-fence/highlighted-code-markdown-extension.test.tsx
@@ -5,12 +5,12 @@
  */
 
 import { render } from '@testing-library/react'
-import { TestMarkdownRenderer } from '../../test-utils/test-markdown-renderer'
 import React from 'react'
 import type { HighlightedCodeProps } from './highlighted-code'
 import * as HighlightedCodeModule from './highlighted-code'
-import { mockI18n } from '../../test-utils/mock-i18n'
 import { HighlightedCodeMarkdownExtension } from './highlighted-code-markdown-extension'
+import { mockI18n } from '../../../components/markdown-renderer/test-utils/mock-i18n'
+import { TestMarkdownRenderer } from '../../../components/markdown-renderer/test-utils/test-markdown-renderer'
 
 jest.mock('./highlighted-code')
 
diff --git a/src/extensions/extra-integrations/highlighted-code-fence/highlighted-code-markdown-extension.ts b/src/extensions/extra-integrations/highlighted-code-fence/highlighted-code-markdown-extension.ts
new file mode 100644
index 000000000..4bcd0fc92
--- /dev/null
+++ b/src/extensions/extra-integrations/highlighted-code-fence/highlighted-code-markdown-extension.ts
@@ -0,0 +1,19 @@
+/*
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import { HighlightedCodeReplacer } from './highlighted-code-replacer'
+import { CodeBlockMarkdownRendererExtension } from '../../../components/markdown-renderer/extensions/base/code-block-markdown-extension/code-block-markdown-renderer-extension'
+import type { ComponentReplacer } from '../../../components/markdown-renderer/replace-components/component-replacer'
+
+/**
+ * Adds code highlighting to the markdown rendering.
+ * Every code fence that is not replaced by another replacer is highlighted using highlight-js.
+ */
+export class HighlightedCodeMarkdownExtension extends CodeBlockMarkdownRendererExtension {
+  public buildReplacers(): ComponentReplacer[] {
+    return [new HighlightedCodeReplacer()]
+  }
+}
diff --git a/src/components/markdown-renderer/markdown-extension/highlighted-fence/highlighted-code-replacer.tsx b/src/extensions/extra-integrations/highlighted-code-fence/highlighted-code-replacer.tsx
similarity index 87%
rename from src/components/markdown-renderer/markdown-extension/highlighted-fence/highlighted-code-replacer.tsx
rename to src/extensions/extra-integrations/highlighted-code-fence/highlighted-code-replacer.tsx
index cf63d2b88..45e1932a7 100644
--- a/src/components/markdown-renderer/markdown-extension/highlighted-fence/highlighted-code-replacer.tsx
+++ b/src/extensions/extra-integrations/highlighted-code-fence/highlighted-code-replacer.tsx
@@ -6,8 +6,11 @@
 
 import type { Element } from 'domhandler'
 import React from 'react'
-import type { NodeReplacement } from '../../replace-components/component-replacer'
-import { ComponentReplacer, DO_NOT_REPLACE } from '../../replace-components/component-replacer'
+import {
+  ComponentReplacer,
+  DO_NOT_REPLACE
+} from '../../../components/markdown-renderer/replace-components/component-replacer'
+import type { NodeReplacement } from '../../../components/markdown-renderer/replace-components/component-replacer'
 import { HighlightedCode } from './highlighted-code'
 
 /**
diff --git a/src/components/markdown-renderer/markdown-extension/highlighted-fence/highlighted-code.module.scss b/src/extensions/extra-integrations/highlighted-code-fence/highlighted-code.module.scss
similarity index 93%
rename from src/components/markdown-renderer/markdown-extension/highlighted-fence/highlighted-code.module.scss
rename to src/extensions/extra-integrations/highlighted-code-fence/highlighted-code.module.scss
index b72bca772..908443205 100644
--- a/src/components/markdown-renderer/markdown-extension/highlighted-fence/highlighted-code.module.scss
+++ b/src/extensions/extra-integrations/highlighted-code-fence/highlighted-code.module.scss
@@ -1,5 +1,5 @@
-/*
- * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+/*!
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
  *
  * SPDX-License-Identifier: AGPL-3.0-only
  */
diff --git a/src/components/markdown-renderer/markdown-extension/highlighted-fence/highlighted-code.test.tsx b/src/extensions/extra-integrations/highlighted-code-fence/highlighted-code.test.tsx
similarity index 95%
rename from src/components/markdown-renderer/markdown-extension/highlighted-fence/highlighted-code.test.tsx
rename to src/extensions/extra-integrations/highlighted-code-fence/highlighted-code.test.tsx
index 1f01b06c7..fd67802b7 100644
--- a/src/components/markdown-renderer/markdown-extension/highlighted-fence/highlighted-code.test.tsx
+++ b/src/extensions/extra-integrations/highlighted-code-fence/highlighted-code.test.tsx
@@ -6,7 +6,7 @@
 
 import { render, screen } from '@testing-library/react'
 import HighlightedCode from './highlighted-code'
-import { mockI18n } from '../../test-utils/mock-i18n'
+import { mockI18n } from '../../../components/markdown-renderer/test-utils/mock-i18n'
 
 describe('Highlighted Code', () => {
   beforeAll(() => mockI18n())
diff --git a/src/components/markdown-renderer/markdown-extension/highlighted-fence/highlighted-code.tsx b/src/extensions/extra-integrations/highlighted-code-fence/highlighted-code.tsx
similarity index 86%
rename from src/components/markdown-renderer/markdown-extension/highlighted-fence/highlighted-code.tsx
rename to src/extensions/extra-integrations/highlighted-code-fence/highlighted-code.tsx
index 78f170d9e..f007c64d6 100644
--- a/src/components/markdown-renderer/markdown-extension/highlighted-fence/highlighted-code.tsx
+++ b/src/extensions/extra-integrations/highlighted-code-fence/highlighted-code.tsx
@@ -5,14 +5,14 @@
  */
 
 import React from 'react'
-import { CopyToClipboardButton } from '../../../common/copyable/copy-to-clipboard-button/copy-to-clipboard-button'
 import styles from './highlighted-code.module.scss'
-import { cypressAttribute, cypressId } from '../../../../utils/cypress-attribute'
-import { AsyncLoadingBoundary } from '../../../common/async-loading-boundary'
 import { useAsyncHighlightJsImport } from './hooks/use-async-highlight-js-import'
 import { useAttachLineNumbers } from './hooks/use-attach-line-numbers'
-import { testId } from '../../../../utils/test-id'
 import { useCodeDom } from './hooks/use-code-dom'
+import { cypressAttribute, cypressId } from '../../../utils/cypress-attribute'
+import { AsyncLoadingBoundary } from '../../../components/common/async-loading-boundary'
+import { CopyToClipboardButton } from '../../../components/common/copyable/copy-to-clipboard-button/copy-to-clipboard-button'
+import { testId } from '../../../utils/test-id'
 
 export interface HighlightedCodeProps {
   code: string
diff --git a/src/components/markdown-renderer/markdown-extension/highlighted-fence/hooks/use-async-highlight-js-import.tsx b/src/extensions/extra-integrations/highlighted-code-fence/hooks/use-async-highlight-js-import.tsx
similarity index 87%
rename from src/components/markdown-renderer/markdown-extension/highlighted-fence/hooks/use-async-highlight-js-import.tsx
rename to src/extensions/extra-integrations/highlighted-code-fence/hooks/use-async-highlight-js-import.tsx
index 511cead54..5f54b02d3 100644
--- a/src/components/markdown-renderer/markdown-extension/highlighted-fence/hooks/use-async-highlight-js-import.tsx
+++ b/src/extensions/extra-integrations/highlighted-code-fence/hooks/use-async-highlight-js-import.tsx
@@ -5,9 +5,9 @@
  */
 
 import { useAsync } from 'react-use'
-import { Logger } from '../../../../../utils/logger'
 import type { AsyncState } from 'react-use/lib/useAsyncFn'
 import type { HLJSApi } from 'highlight.js'
+import { Logger } from '../../../../utils/logger'
 
 const log = new Logger('HighlightedCode')
 
@@ -19,7 +19,7 @@ const log = new Logger('HighlightedCode')
 export const useAsyncHighlightJsImport = (): AsyncState<HLJSApi> => {
   return useAsync(async () => {
     try {
-      return (await import(/* webpackChunkName: "highlight.js" */ '../../../../common/hljs/hljs')).default
+      return (await import(/* webpackChunkName: "highlight.js" */ '../preconfigured-highlight-js')).default
     } catch (error) {
       log.error('Error while loading highlight.js', error)
       throw error
diff --git a/src/components/markdown-renderer/markdown-extension/highlighted-fence/hooks/use-attach-line-numbers.tsx b/src/extensions/extra-integrations/highlighted-code-fence/hooks/use-attach-line-numbers.tsx
similarity index 93%
rename from src/components/markdown-renderer/markdown-extension/highlighted-fence/hooks/use-attach-line-numbers.tsx
rename to src/extensions/extra-integrations/highlighted-code-fence/hooks/use-attach-line-numbers.tsx
index a47b8d6ab..6894fd4d9 100644
--- a/src/components/markdown-renderer/markdown-extension/highlighted-fence/hooks/use-attach-line-numbers.tsx
+++ b/src/extensions/extra-integrations/highlighted-code-fence/hooks/use-attach-line-numbers.tsx
@@ -6,8 +6,8 @@
 
 import type { ReactElement } from 'react'
 import { Fragment, useMemo } from 'react'
-import { cypressId } from '../../../../../utils/cypress-attribute'
 import styles from '../highlighted-code.module.scss'
+import { cypressId } from '../../../../utils/cypress-attribute'
 
 /**
  * Wraps the given {@link ReactElement elements} to attach line numbers to them.
diff --git a/src/components/markdown-renderer/markdown-extension/highlighted-fence/hooks/use-code-dom.tsx b/src/extensions/extra-integrations/highlighted-code-fence/hooks/use-code-dom.tsx
similarity index 100%
rename from src/components/markdown-renderer/markdown-extension/highlighted-fence/hooks/use-code-dom.tsx
rename to src/extensions/extra-integrations/highlighted-code-fence/hooks/use-code-dom.tsx
diff --git a/src/components/common/hljs/hljs.ts b/src/extensions/extra-integrations/highlighted-code-fence/preconfigured-highlight-js.ts
similarity index 99%
rename from src/components/common/hljs/hljs.ts
rename to src/extensions/extra-integrations/highlighted-code-fence/preconfigured-highlight-js.ts
index 983fafd35..57cfceb40 100644
--- a/src/components/common/hljs/hljs.ts
+++ b/src/extensions/extra-integrations/highlighted-code-fence/preconfigured-highlight-js.ts
@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
  *
  * SPDX-License-Identifier: AGPL-3.0-only
  */
diff --git a/src/components/markdown-renderer/markdown-extension/katex/__snapshots__/katex-frame.test.tsx.snap b/src/extensions/extra-integrations/katex/__snapshots__/katex-frame.test.tsx.snap
similarity index 100%
rename from src/components/markdown-renderer/markdown-extension/katex/__snapshots__/katex-frame.test.tsx.snap
rename to src/extensions/extra-integrations/katex/__snapshots__/katex-frame.test.tsx.snap
diff --git a/src/components/markdown-renderer/markdown-extension/katex/__snapshots__/katex-markdown-extension.test.tsx.snap b/src/extensions/extra-integrations/katex/__snapshots__/katex-markdown-extension.test.tsx.snap
similarity index 100%
rename from src/components/markdown-renderer/markdown-extension/katex/__snapshots__/katex-markdown-extension.test.tsx.snap
rename to src/extensions/extra-integrations/katex/__snapshots__/katex-markdown-extension.test.tsx.snap
diff --git a/src/extensions/extra-integrations/katex/katex-app-extension.ts b/src/extensions/extra-integrations/katex/katex-app-extension.ts
new file mode 100644
index 000000000..ad0a8e651
--- /dev/null
+++ b/src/extensions/extra-integrations/katex/katex-app-extension.ts
@@ -0,0 +1,20 @@
+/*
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import { AppExtension } from '../../base/app-extension'
+import type { MarkdownRendererExtension } from '../../../components/markdown-renderer/extensions/base/markdown-renderer-extension'
+import { KatexMarkdownExtension } from './katex-markdown-extension'
+
+/**
+ * Adds support for LaTeX rendering using KaTeX to the markdown rendering.
+ *
+ * @see https://katex.org/
+ */
+export class KatexAppExtension extends AppExtension {
+  buildMarkdownRendererExtensions(): MarkdownRendererExtension[] {
+    return [new KatexMarkdownExtension()]
+  }
+}
diff --git a/src/components/markdown-renderer/markdown-extension/katex/katex-frame.test.tsx b/src/extensions/extra-integrations/katex/katex-frame.test.tsx
similarity index 100%
rename from src/components/markdown-renderer/markdown-extension/katex/katex-frame.test.tsx
rename to src/extensions/extra-integrations/katex/katex-frame.test.tsx
diff --git a/src/components/markdown-renderer/markdown-extension/katex/katex-frame.tsx b/src/extensions/extra-integrations/katex/katex-frame.tsx
similarity index 96%
rename from src/components/markdown-renderer/markdown-extension/katex/katex-frame.tsx
rename to src/extensions/extra-integrations/katex/katex-frame.tsx
index c7ae3c0cf..34e95cffd 100644
--- a/src/components/markdown-renderer/markdown-extension/katex/katex-frame.tsx
+++ b/src/extensions/extra-integrations/katex/katex-frame.tsx
@@ -9,8 +9,8 @@ import KaTeX from 'katex'
 import convertHtmlToReact from '@hedgedoc/html-to-react'
 import 'katex/dist/katex.min.css'
 import { Alert } from 'react-bootstrap'
-import { testId } from '../../../../utils/test-id'
 import { sanitize } from 'dompurify'
+import { testId } from '../../../utils/test-id'
 
 interface KatexFrameProps {
   expression: string
diff --git a/src/components/markdown-renderer/markdown-extension/katex/katex-markdown-extension.test.tsx b/src/extensions/extra-integrations/katex/katex-markdown-extension.test.tsx
similarity index 95%
rename from src/components/markdown-renderer/markdown-extension/katex/katex-markdown-extension.test.tsx
rename to src/extensions/extra-integrations/katex/katex-markdown-extension.test.tsx
index 1294d3fe2..94de9bc4b 100644
--- a/src/components/markdown-renderer/markdown-extension/katex/katex-markdown-extension.test.tsx
+++ b/src/extensions/extra-integrations/katex/katex-markdown-extension.test.tsx
@@ -6,10 +6,10 @@
 
 import { render, screen } from '@testing-library/react'
 import { KatexMarkdownExtension } from './katex-markdown-extension'
-import { TestMarkdownRenderer } from '../../test-utils/test-markdown-renderer'
 import { Suspense } from 'react'
 import type { KatexOptions } from 'katex'
 import { default as KatexDefault } from 'katex'
+import { TestMarkdownRenderer } from '../../../components/markdown-renderer/test-utils/test-markdown-renderer'
 
 jest.mock('katex')
 
diff --git a/src/components/markdown-renderer/markdown-extension/katex/katex-markdown-extension.ts b/src/extensions/extra-integrations/katex/katex-markdown-extension.ts
similarity index 77%
rename from src/components/markdown-renderer/markdown-extension/katex/katex-markdown-extension.ts
rename to src/extensions/extra-integrations/katex/katex-markdown-extension.ts
index c00e369e3..6f041ab4e 100644
--- a/src/components/markdown-renderer/markdown-extension/katex/katex-markdown-extension.ts
+++ b/src/extensions/extra-integrations/katex/katex-markdown-extension.ts
@@ -4,18 +4,18 @@
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
-import { MarkdownExtension } from '../markdown-extension'
 import mathJax from 'markdown-it-mathjax'
 import type MarkdownIt from 'markdown-it'
-import type { ComponentReplacer } from '../../replace-components/component-replacer'
 import { KatexReplacer } from './katex-replacer'
+import type { ComponentReplacer } from '../../../components/markdown-renderer/replace-components/component-replacer'
+import { MarkdownRendererExtension } from '../../../components/markdown-renderer/extensions/base/markdown-renderer-extension'
 
 /**
  * Adds support for rendering of LaTeX code using KaTeX.
  *
  * @see https://katex.org/
  */
-export class KatexMarkdownExtension extends MarkdownExtension {
+export class KatexMarkdownExtension extends MarkdownRendererExtension {
   public static readonly tagName = 'app-katex'
 
   public configureMarkdownIt(markdownIt: MarkdownIt): void {
diff --git a/src/components/markdown-renderer/markdown-extension/katex/katex-replacer.tsx b/src/extensions/extra-integrations/katex/katex-replacer.tsx
similarity index 90%
rename from src/components/markdown-renderer/markdown-extension/katex/katex-replacer.tsx
rename to src/extensions/extra-integrations/katex/katex-replacer.tsx
index 9f7f00d30..126caf2aa 100644
--- a/src/components/markdown-renderer/markdown-extension/katex/katex-replacer.tsx
+++ b/src/extensions/extra-integrations/katex/katex-replacer.tsx
@@ -7,8 +7,11 @@
 import type { Element } from 'domhandler'
 import { isTag } from 'domhandler'
 import React from 'react'
-import type { NodeReplacement } from '../../replace-components/component-replacer'
-import { ComponentReplacer, DO_NOT_REPLACE } from '../../replace-components/component-replacer'
+import type { NodeReplacement } from '../../../components/markdown-renderer/replace-components/component-replacer'
+import {
+  ComponentReplacer,
+  DO_NOT_REPLACE
+} from '../../../components/markdown-renderer/replace-components/component-replacer'
 import { KatexMarkdownExtension } from './katex-markdown-extension'
 import { Optional } from '@mrdrogdrog/optional'
 
diff --git a/src/components/markdown-renderer/markdown-extension/legacy-short-codes/__snapshots__/legacy-shortcodes-markdown-extension.test.tsx.snap b/src/extensions/extra-integrations/legacy-short-codes/__snapshots__/legacy-shortcodes-markdown-extension.test.tsx.snap
similarity index 100%
rename from src/components/markdown-renderer/markdown-extension/legacy-short-codes/__snapshots__/legacy-shortcodes-markdown-extension.test.tsx.snap
rename to src/extensions/extra-integrations/legacy-short-codes/__snapshots__/legacy-shortcodes-markdown-extension.test.tsx.snap
diff --git a/src/extensions/extra-integrations/legacy-short-codes/legacy-shortcodes-app-extension.ts b/src/extensions/extra-integrations/legacy-short-codes/legacy-shortcodes-app-extension.ts
new file mode 100644
index 000000000..fd8a0849f
--- /dev/null
+++ b/src/extensions/extra-integrations/legacy-short-codes/legacy-shortcodes-app-extension.ts
@@ -0,0 +1,43 @@
+/*
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+import { AppExtension } from '../../base/app-extension'
+import type { MarkdownRendererExtension } from '../../../components/markdown-renderer/extensions/base/markdown-renderer-extension'
+import { LegacyShortcodesMarkdownExtension } from './legacy-shortcodes-markdown-extension'
+import type { Linter } from '../../../components/editor-page/editor-pane/linter/linter'
+import { SingleLineRegexLinter } from '../../../components/editor-page/editor-pane/linter/single-line-regex-linter'
+import { legacySpeakerdeckRegex } from './replace-legacy-speakerdeck-short-code'
+import { t } from 'i18next'
+import { legacySlideshareRegex } from './replace-legacy-slideshare-short-code'
+import { legacyPdfRegex } from './replace-legacy-pdf-short-code'
+
+/**
+ * Adds support for legacy shortcodes (pdf, slideshare and speakerdeck) from HedgeDoc 1 to the markdown renderer.
+ */
+export class LegacyShortcodesAppExtension extends AppExtension {
+  buildMarkdownRendererExtensions(): MarkdownRendererExtension[] {
+    return [new LegacyShortcodesMarkdownExtension()]
+  }
+
+  buildCodeMirrorLinter(): Linter[] {
+    return [
+      new SingleLineRegexLinter(
+        legacySpeakerdeckRegex,
+        t('editor.linter.shortcode', { shortcode: 'SpeakerDeck' }),
+        (match: string) => `https://speakerdeck.com/${match}`
+      ),
+      new SingleLineRegexLinter(
+        legacySlideshareRegex,
+        t('editor.linter.shortcode', { shortcode: 'SlideShare' }),
+        (match: string) => `https://www.slideshare.net/${match}`
+      ),
+      new SingleLineRegexLinter(
+        legacyPdfRegex,
+        t('editor.linter.shortcode', { shortcode: 'PDF' }),
+        (match: string) => match
+      )
+    ]
+  }
+}
diff --git a/src/components/markdown-renderer/markdown-extension/legacy-short-codes/legacy-shortcodes-markdown-extension.test.tsx b/src/extensions/extra-integrations/legacy-short-codes/legacy-shortcodes-markdown-extension.test.tsx
similarity index 92%
rename from src/components/markdown-renderer/markdown-extension/legacy-short-codes/legacy-shortcodes-markdown-extension.test.tsx
rename to src/extensions/extra-integrations/legacy-short-codes/legacy-shortcodes-markdown-extension.test.tsx
index b5fb509be..9a0d4f708 100644
--- a/src/components/markdown-renderer/markdown-extension/legacy-short-codes/legacy-shortcodes-markdown-extension.test.tsx
+++ b/src/extensions/extra-integrations/legacy-short-codes/legacy-shortcodes-markdown-extension.test.tsx
@@ -4,9 +4,9 @@
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 import { render } from '@testing-library/react'
-import { TestMarkdownRenderer } from '../../test-utils/test-markdown-renderer'
 import React from 'react'
 import { LegacyShortcodesMarkdownExtension } from './legacy-shortcodes-markdown-extension'
+import { TestMarkdownRenderer } from '../../../components/markdown-renderer/test-utils/test-markdown-renderer'
 
 describe('Legacy shortcodes markdown extension', () => {
   it('transforms a pdf short code into an URL', () => {
diff --git a/src/extensions/extra-integrations/legacy-short-codes/legacy-shortcodes-markdown-extension.ts b/src/extensions/extra-integrations/legacy-short-codes/legacy-shortcodes-markdown-extension.ts
new file mode 100644
index 000000000..da08ec1e6
--- /dev/null
+++ b/src/extensions/extra-integrations/legacy-short-codes/legacy-shortcodes-markdown-extension.ts
@@ -0,0 +1,22 @@
+/*
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import type MarkdownIt from 'markdown-it'
+import { legacyPdfShortCode } from './replace-legacy-pdf-short-code'
+import { legacySlideshareShortCode } from './replace-legacy-slideshare-short-code'
+import { legacySpeakerdeckShortCode } from './replace-legacy-speakerdeck-short-code'
+import { MarkdownRendererExtension } from '../../../components/markdown-renderer/extensions/base/markdown-renderer-extension'
+
+/**
+ * Adds support for legacy shortcodes (pdf, slideshare and speakerdeck) by replacing them with anchor elements.
+ */
+export class LegacyShortcodesMarkdownExtension extends MarkdownRendererExtension {
+  public configureMarkdownIt(markdownIt: MarkdownIt): void {
+    legacyPdfShortCode(markdownIt)
+    legacySlideshareShortCode(markdownIt)
+    legacySpeakerdeckShortCode(markdownIt)
+  }
+}
diff --git a/src/components/markdown-renderer/markdown-extension/legacy-short-codes/replace-legacy-pdf-short-code.test.ts b/src/extensions/extra-integrations/legacy-short-codes/replace-legacy-pdf-short-code.test.ts
similarity index 100%
rename from src/components/markdown-renderer/markdown-extension/legacy-short-codes/replace-legacy-pdf-short-code.test.ts
rename to src/extensions/extra-integrations/legacy-short-codes/replace-legacy-pdf-short-code.test.ts
diff --git a/src/components/markdown-renderer/markdown-extension/legacy-short-codes/replace-legacy-pdf-short-code.ts b/src/extensions/extra-integrations/legacy-short-codes/replace-legacy-pdf-short-code.ts
similarity index 88%
rename from src/components/markdown-renderer/markdown-extension/legacy-short-codes/replace-legacy-pdf-short-code.ts
rename to src/extensions/extra-integrations/legacy-short-codes/replace-legacy-pdf-short-code.ts
index 5670e102c..fe1436053 100644
--- a/src/components/markdown-renderer/markdown-extension/legacy-short-codes/replace-legacy-pdf-short-code.ts
+++ b/src/extensions/extra-integrations/legacy-short-codes/replace-legacy-pdf-short-code.ts
@@ -6,7 +6,7 @@
 
 import markdownItRegex from 'markdown-it-regex'
 import type MarkdownIt from 'markdown-it/lib'
-import type { RegexOptions } from '../../../../external-types/markdown-it-regex/interface'
+import type { RegexOptions } from '../../../external-types/markdown-it-regex/interface'
 
 export const legacyPdfRegex = /^{%pdf\s+(\S*)\s*%}$/
 
diff --git a/src/components/markdown-renderer/markdown-extension/legacy-short-codes/replace-legacy-slideshare-short-code.test.ts b/src/extensions/extra-integrations/legacy-short-codes/replace-legacy-slideshare-short-code.test.ts
similarity index 100%
rename from src/components/markdown-renderer/markdown-extension/legacy-short-codes/replace-legacy-slideshare-short-code.test.ts
rename to src/extensions/extra-integrations/legacy-short-codes/replace-legacy-slideshare-short-code.test.ts
diff --git a/src/components/markdown-renderer/markdown-extension/legacy-short-codes/replace-legacy-slideshare-short-code.ts b/src/extensions/extra-integrations/legacy-short-codes/replace-legacy-slideshare-short-code.ts
similarity index 89%
rename from src/components/markdown-renderer/markdown-extension/legacy-short-codes/replace-legacy-slideshare-short-code.ts
rename to src/extensions/extra-integrations/legacy-short-codes/replace-legacy-slideshare-short-code.ts
index 70771a574..2f0621c7e 100644
--- a/src/components/markdown-renderer/markdown-extension/legacy-short-codes/replace-legacy-slideshare-short-code.ts
+++ b/src/extensions/extra-integrations/legacy-short-codes/replace-legacy-slideshare-short-code.ts
@@ -6,7 +6,7 @@
 
 import markdownItRegex from 'markdown-it-regex'
 import type MarkdownIt from 'markdown-it/lib'
-import type { RegexOptions } from '../../../../external-types/markdown-it-regex/interface'
+import type { RegexOptions } from '../../../external-types/markdown-it-regex/interface'
 
 export const legacySlideshareRegex = /^{%slideshare\s+(\w+\/[\w-]+)\s*%}$/
 
diff --git a/src/components/markdown-renderer/markdown-extension/legacy-short-codes/replace-legacy-speakerdeck-short-code.test.ts b/src/extensions/extra-integrations/legacy-short-codes/replace-legacy-speakerdeck-short-code.test.ts
similarity index 100%
rename from src/components/markdown-renderer/markdown-extension/legacy-short-codes/replace-legacy-speakerdeck-short-code.test.ts
rename to src/extensions/extra-integrations/legacy-short-codes/replace-legacy-speakerdeck-short-code.test.ts
diff --git a/src/components/markdown-renderer/markdown-extension/legacy-short-codes/replace-legacy-speakerdeck-short-code.ts b/src/extensions/extra-integrations/legacy-short-codes/replace-legacy-speakerdeck-short-code.ts
similarity index 89%
rename from src/components/markdown-renderer/markdown-extension/legacy-short-codes/replace-legacy-speakerdeck-short-code.ts
rename to src/extensions/extra-integrations/legacy-short-codes/replace-legacy-speakerdeck-short-code.ts
index d0d433e48..a779f1e9e 100644
--- a/src/components/markdown-renderer/markdown-extension/legacy-short-codes/replace-legacy-speakerdeck-short-code.ts
+++ b/src/extensions/extra-integrations/legacy-short-codes/replace-legacy-speakerdeck-short-code.ts
@@ -6,7 +6,7 @@
 
 import markdownItRegex from 'markdown-it-regex'
 import type MarkdownIt from 'markdown-it/lib'
-import type { RegexOptions } from '../../../../external-types/markdown-it-regex/interface'
+import type { RegexOptions } from '../../../external-types/markdown-it-regex/interface'
 
 export const legacySpeakerdeckRegex = /^{%speakerdeck\s+(\w+\/[\w-]+)\s*%}$/
 
diff --git a/src/extensions/extra-integrations/mermaid/mermaid-app-extension.ts b/src/extensions/extra-integrations/mermaid/mermaid-app-extension.ts
new file mode 100644
index 000000000..8b58b254a
--- /dev/null
+++ b/src/extensions/extra-integrations/mermaid/mermaid-app-extension.ts
@@ -0,0 +1,18 @@
+/*
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import { AppExtension } from '../../base/app-extension'
+import type { MarkdownRendererExtension } from '../../../components/markdown-renderer/extensions/base/markdown-renderer-extension'
+import { MermaidMarkdownExtension } from './mermaid-markdown-extension'
+
+/**
+ * Adds support for chart rendering using mermaid to the markdown renderer.
+ */
+export class MermaidAppExtension extends AppExtension {
+  buildMarkdownRendererExtensions(): MarkdownRendererExtension[] {
+    return [new MermaidMarkdownExtension()]
+  }
+}
diff --git a/src/components/markdown-renderer/markdown-extension/mermaid/mermaid-chart.tsx b/src/extensions/extra-integrations/mermaid/mermaid-chart.tsx
similarity index 89%
rename from src/components/markdown-renderer/markdown-extension/mermaid/mermaid-chart.tsx
rename to src/extensions/extra-integrations/mermaid/mermaid-chart.tsx
index c0ca94012..b1f16ce91 100644
--- a/src/components/markdown-renderer/markdown-extension/mermaid/mermaid-chart.tsx
+++ b/src/extensions/extra-integrations/mermaid/mermaid-chart.tsx
@@ -7,11 +7,11 @@
 import React, { Fragment, useCallback, useEffect, useRef, useState } from 'react'
 import { Alert } from 'react-bootstrap'
 import { useTranslation } from 'react-i18next'
-import { ShowIf } from '../../../common/show-if/show-if'
 import styles from './mermaid.module.scss'
-import { Logger } from '../../../../utils/logger'
-import type { CodeProps } from '../../replace-components/code-block-component-replacer'
-import { cypressId } from '../../../../utils/cypress-attribute'
+import type { CodeProps } from '../../../components/markdown-renderer/replace-components/code-block-component-replacer'
+import { cypressId } from '../../../utils/cypress-attribute'
+import { ShowIf } from '../../../components/common/show-if/show-if'
+import { Logger } from '../../../utils/logger'
 
 const log = new Logger('MermaidChart')
 
diff --git a/src/extensions/extra-integrations/mermaid/mermaid-markdown-extension.ts b/src/extensions/extra-integrations/mermaid/mermaid-markdown-extension.ts
new file mode 100644
index 000000000..616e6e8f0
--- /dev/null
+++ b/src/extensions/extra-integrations/mermaid/mermaid-markdown-extension.ts
@@ -0,0 +1,18 @@
+/*
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import { MermaidChart } from './mermaid-chart'
+import { CodeBlockMarkdownRendererExtension } from '../../../components/markdown-renderer/extensions/base/code-block-markdown-extension/code-block-markdown-renderer-extension'
+import { CodeBlockComponentReplacer } from '../../../components/markdown-renderer/replace-components/code-block-component-replacer'
+
+/**
+ * Adds support for chart rendering using mermaid to the markdown rendering using code fences with "mermaid" as language.
+ */
+export class MermaidMarkdownExtension extends CodeBlockMarkdownRendererExtension {
+  public buildReplacers(): CodeBlockComponentReplacer[] {
+    return [new CodeBlockComponentReplacer(MermaidChart, 'mermaid')]
+  }
+}
diff --git a/src/components/markdown-renderer/markdown-extension/mermaid/mermaid.module.scss b/src/extensions/extra-integrations/mermaid/mermaid.module.scss
similarity index 61%
rename from src/components/markdown-renderer/markdown-extension/mermaid/mermaid.module.scss
rename to src/extensions/extra-integrations/mermaid/mermaid.module.scss
index 5fa41b32e..0b3f568fb 100644
--- a/src/components/markdown-renderer/markdown-extension/mermaid/mermaid.module.scss
+++ b/src/extensions/extra-integrations/mermaid/mermaid.module.scss
@@ -1,5 +1,5 @@
-/*
- * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+/*!
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
  *
  * SPDX-License-Identifier: AGPL-3.0-only
  */
diff --git a/src/extensions/extra-integrations/optional-app-extensions.ts b/src/extensions/extra-integrations/optional-app-extensions.ts
new file mode 100644
index 000000000..9411bb415
--- /dev/null
+++ b/src/extensions/extra-integrations/optional-app-extensions.ts
@@ -0,0 +1,49 @@
+/*
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import { AbcjsAppExtension } from './abcjs/abcjs-app-extension'
+import { AlertAppExtension } from './alert/alert-app-extension'
+import { BlockquoteAppExtension } from './blockquote/blockquote-app-extension'
+import { CsvTableAppExtension } from './csv/csv-table-app-extension'
+import { FlowchartAppExtension } from './flowchart/flowchart-app-extension'
+import { GistAppExtension } from './gist/gist-app-extension'
+import { GraphvizAppExtension } from './graphviz/graphviz-app-extension'
+import { KatexAppExtension } from './katex/katex-app-extension'
+import { LegacyShortcodesAppExtension } from './legacy-short-codes/legacy-shortcodes-app-extension'
+import { MermaidAppExtension } from './mermaid/mermaid-app-extension'
+import { PlantumlAppExtension } from './plantuml/plantuml-app-extension'
+import { LegacySequenceDiagramAppExtension } from './sequence-diagram/legacy-sequence-diagram-app-extension'
+import { SpoilerAppExtension } from './spoiler/spoiler-app-extension'
+import { VegaLiteAppExtension } from './vega-lite/vega-lite-app-extension'
+import { VimeoAppExtension } from './vimeo/vimeo-app-extension'
+import { YoutubeAppExtension } from './youtube/youtube-app-extension'
+import { HighlightedCodeFenceAppExtension } from './highlighted-code-fence/highlighted-code-fence-app-extension'
+import type { AppExtension } from '../base/app-extension'
+import { TaskListCheckboxAppExtension } from './task-list/task-list-checkbox-app-extension'
+
+/**
+ * This array defines additional app extensions that are used in the editor, read only page and slideshow.
+ */
+export const optionalAppExtensions: AppExtension[] = [
+  new AbcjsAppExtension(),
+  new AlertAppExtension(),
+  new BlockquoteAppExtension(),
+  new CsvTableAppExtension(),
+  new FlowchartAppExtension(),
+  new GistAppExtension(),
+  new GraphvizAppExtension(),
+  new KatexAppExtension(),
+  new LegacyShortcodesAppExtension(),
+  new MermaidAppExtension(),
+  new PlantumlAppExtension(),
+  new LegacySequenceDiagramAppExtension(),
+  new SpoilerAppExtension(),
+  new VegaLiteAppExtension(),
+  new VimeoAppExtension(),
+  new YoutubeAppExtension(),
+  new TaskListCheckboxAppExtension(),
+  new HighlightedCodeFenceAppExtension()
+]
diff --git a/src/components/markdown-renderer/markdown-extension/plantuml/__snapshots__/plantuml-markdown-extension.test.tsx.snap b/src/extensions/extra-integrations/plantuml/__snapshots__/plantuml-markdown-extension.test.tsx.snap
similarity index 100%
rename from src/components/markdown-renderer/markdown-extension/plantuml/__snapshots__/plantuml-markdown-extension.test.tsx.snap
rename to src/extensions/extra-integrations/plantuml/__snapshots__/plantuml-markdown-extension.test.tsx.snap
diff --git a/src/extensions/extra-integrations/plantuml/plantuml-app-extension.ts b/src/extensions/extra-integrations/plantuml/plantuml-app-extension.ts
new file mode 100644
index 000000000..fb152466a
--- /dev/null
+++ b/src/extensions/extra-integrations/plantuml/plantuml-app-extension.ts
@@ -0,0 +1,20 @@
+/*
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import { AppExtension } from '../../base/app-extension'
+import type { MarkdownRendererExtension } from '../../../components/markdown-renderer/extensions/base/markdown-renderer-extension'
+import { PlantumlMarkdownExtension } from './plantuml-markdown-extension'
+
+/**
+ * Adds support for chart rendering using plantuml to the markdown renderer.
+ *
+ * @see https://plantuml.com
+ */
+export class PlantumlAppExtension extends AppExtension {
+  buildMarkdownRendererExtensions(): MarkdownRendererExtension[] {
+    return [new PlantumlMarkdownExtension()]
+  }
+}
diff --git a/src/components/markdown-renderer/markdown-extension/plantuml/plantuml-markdown-extension.test.tsx b/src/extensions/extra-integrations/plantuml/plantuml-markdown-extension.test.tsx
similarity index 77%
rename from src/components/markdown-renderer/markdown-extension/plantuml/plantuml-markdown-extension.test.tsx
rename to src/extensions/extra-integrations/plantuml/plantuml-markdown-extension.test.tsx
index c352df4e5..a861822e4 100644
--- a/src/components/markdown-renderer/markdown-extension/plantuml/plantuml-markdown-extension.test.tsx
+++ b/src/extensions/extra-integrations/plantuml/plantuml-markdown-extension.test.tsx
@@ -5,20 +5,18 @@
  */
 
 import { render } from '@testing-library/react'
-import { TestMarkdownRenderer } from '../../test-utils/test-markdown-renderer'
 import React from 'react'
 import { PlantumlMarkdownExtension } from './plantuml-markdown-extension'
-import { mockI18n } from '../../test-utils/mock-i18n'
-import * as reduxModule from '../../../../redux'
+import * as reduxModule from '../../../redux'
 import { Mock } from 'ts-mockery'
-import type { ApplicationState } from '../../../../redux/application-state'
+import { mockI18n } from '../../../components/markdown-renderer/test-utils/mock-i18n'
+import type { ApplicationState } from '../../../redux/application-state'
+import { TestMarkdownRenderer } from '../../../components/markdown-renderer/test-utils/test-markdown-renderer'
 
-jest.mock('../../../../redux')
+jest.mock('../../../redux')
 
 describe('PlantUML markdown extensions', () => {
-  beforeAll(async () => {
-    await mockI18n()
-  })
+  beforeAll(() => mockI18n())
 
   it('renders a plantuml codeblock', () => {
     jest.spyOn(reduxModule, 'getGlobalState').mockReturnValue(
diff --git a/src/components/markdown-renderer/markdown-extension/plantuml/plantuml-markdown-extension.ts b/src/extensions/extra-integrations/plantuml/plantuml-markdown-extension.ts
similarity index 82%
rename from src/components/markdown-renderer/markdown-extension/plantuml/plantuml-markdown-extension.ts
rename to src/extensions/extra-integrations/plantuml/plantuml-markdown-extension.ts
index ce5c22ebf..fcd1c68e4 100644
--- a/src/components/markdown-renderer/markdown-extension/plantuml/plantuml-markdown-extension.ts
+++ b/src/extensions/extra-integrations/plantuml/plantuml-markdown-extension.ts
@@ -4,23 +4,23 @@
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
-import { MarkdownExtension } from '../markdown-extension'
 import type MarkdownIt from 'markdown-it'
 import plantuml from 'markdown-it-plantuml'
 import type Renderer from 'markdown-it/lib/renderer'
 import type Token from 'markdown-it/lib/token'
 import type { Options } from 'markdown-it/lib'
-import type { ComponentReplacer } from '../../replace-components/component-replacer'
 import { PlantumlNotConfiguredComponentReplacer } from './plantuml-not-configured-component-replacer'
-import { getGlobalState } from '../../../../redux'
 import { Optional } from '@mrdrogdrog/optional'
+import type { ComponentReplacer } from '../../../components/markdown-renderer/replace-components/component-replacer'
+import { getGlobalState } from '../../../redux'
+import { MarkdownRendererExtension } from '../../../components/markdown-renderer/extensions/base/markdown-renderer-extension'
 
 /**
  * Adds support for chart rendering using plantuml to the markdown rendering using code fences with "plantuml" as language.
  *
  * @see https://plantuml.com
  */
-export class PlantumlMarkdownExtension extends MarkdownExtension {
+export class PlantumlMarkdownExtension extends MarkdownRendererExtension {
   constructor() {
     super()
   }
diff --git a/src/components/markdown-renderer/markdown-extension/plantuml/plantuml-not-configured-alert.tsx b/src/extensions/extra-integrations/plantuml/plantuml-not-configured-alert.tsx
similarity index 100%
rename from src/components/markdown-renderer/markdown-extension/plantuml/plantuml-not-configured-alert.tsx
rename to src/extensions/extra-integrations/plantuml/plantuml-not-configured-alert.tsx
diff --git a/src/components/markdown-renderer/markdown-extension/plantuml/plantuml-not-configured-component-replacer.tsx b/src/extensions/extra-integrations/plantuml/plantuml-not-configured-component-replacer.tsx
similarity index 70%
rename from src/components/markdown-renderer/markdown-extension/plantuml/plantuml-not-configured-component-replacer.tsx
rename to src/extensions/extra-integrations/plantuml/plantuml-not-configured-component-replacer.tsx
index 5d243718b..b195169b7 100644
--- a/src/components/markdown-renderer/markdown-extension/plantuml/plantuml-not-configured-component-replacer.tsx
+++ b/src/extensions/extra-integrations/plantuml/plantuml-not-configured-component-replacer.tsx
@@ -4,10 +4,13 @@
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
-import type { NodeReplacement } from '../../replace-components/component-replacer'
-import { ComponentReplacer, DO_NOT_REPLACE } from '../../replace-components/component-replacer'
 import { PlantumlNotConfiguredAlert } from './plantuml-not-configured-alert'
 import type { Element } from 'domhandler'
+import type { NodeReplacement } from '../../../components/markdown-renderer/replace-components/component-replacer'
+import {
+  ComponentReplacer,
+  DO_NOT_REPLACE
+} from '../../../components/markdown-renderer/replace-components/component-replacer'
 
 /**
  * Replaces every plantuml-not-configured tag with a {@link PlantumlNotConfiguredAlert}.
diff --git a/src/extensions/extra-integrations/sequence-diagram/legacy-sequence-diagram-app-extension.ts b/src/extensions/extra-integrations/sequence-diagram/legacy-sequence-diagram-app-extension.ts
new file mode 100644
index 000000000..c926a7b57
--- /dev/null
+++ b/src/extensions/extra-integrations/sequence-diagram/legacy-sequence-diagram-app-extension.ts
@@ -0,0 +1,25 @@
+/*
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import { AppExtension } from '../../base/app-extension'
+import type { MarkdownRendererExtension } from '../../../components/markdown-renderer/extensions/base/markdown-renderer-extension'
+import { LegacySequenceDiagramMarkdownExtension } from './legacy-sequence-diagram-markdown-extension'
+import type { Linter } from '../../../components/editor-page/editor-pane/linter/linter'
+import { SingleLineRegexLinter } from '../../../components/editor-page/editor-pane/linter/single-line-regex-linter'
+import { t } from 'i18next'
+
+/**
+ * Adds legacy support for sequence diagram syntax to the markdown renderer.
+ */
+export class LegacySequenceDiagramAppExtension extends AppExtension {
+  buildMarkdownRendererExtensions(): MarkdownRendererExtension[] {
+    return [new LegacySequenceDiagramMarkdownExtension()]
+  }
+
+  buildCodeMirrorLinter(): Linter[] {
+    return [new SingleLineRegexLinter(/```sequence/, t('editor.linter.sequence'), () => '```mermaid\nsequenceDiagram')]
+  }
+}
diff --git a/src/extensions/extra-integrations/sequence-diagram/legacy-sequence-diagram-markdown-extension.ts b/src/extensions/extra-integrations/sequence-diagram/legacy-sequence-diagram-markdown-extension.ts
new file mode 100644
index 000000000..26bae1fe6
--- /dev/null
+++ b/src/extensions/extra-integrations/sequence-diagram/legacy-sequence-diagram-markdown-extension.ts
@@ -0,0 +1,18 @@
+/*
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import { SequenceDiagram } from './sequence-diagram'
+import { CodeBlockMarkdownRendererExtension } from '../../../components/markdown-renderer/extensions/base/code-block-markdown-extension/code-block-markdown-renderer-extension'
+import { CodeBlockComponentReplacer } from '../../../components/markdown-renderer/replace-components/code-block-component-replacer'
+
+/**
+ * Adds legacy support for sequence diagram to the markdown rendering using code fences with "sequence" as language.
+ */
+export class LegacySequenceDiagramMarkdownExtension extends CodeBlockMarkdownRendererExtension {
+  public buildReplacers(): CodeBlockComponentReplacer[] {
+    return [new CodeBlockComponentReplacer(SequenceDiagram, 'sequence')]
+  }
+}
diff --git a/src/components/markdown-renderer/markdown-extension/sequence-diagram/sequence-diagram.tsx b/src/extensions/extra-integrations/sequence-diagram/sequence-diagram.tsx
similarity index 78%
rename from src/components/markdown-renderer/markdown-extension/sequence-diagram/sequence-diagram.tsx
rename to src/extensions/extra-integrations/sequence-diagram/sequence-diagram.tsx
index 08f1a9d64..a19837a0a 100644
--- a/src/components/markdown-renderer/markdown-extension/sequence-diagram/sequence-diagram.tsx
+++ b/src/extensions/extra-integrations/sequence-diagram/sequence-diagram.tsx
@@ -5,8 +5,8 @@
  */
 
 import React from 'react'
-import type { CodeProps } from '../../replace-components/code-block-component-replacer'
 import { MermaidChart } from '../mermaid/mermaid-chart'
+import type { CodeProps } from '../../../components/markdown-renderer/replace-components/code-block-component-replacer'
 
 /**
  * Renders a sequence diagram with a deprecation notice.
diff --git a/src/extensions/extra-integrations/spoiler/spoiler-app-extension.ts b/src/extensions/extra-integrations/spoiler/spoiler-app-extension.ts
new file mode 100644
index 000000000..d09f0dcd9
--- /dev/null
+++ b/src/extensions/extra-integrations/spoiler/spoiler-app-extension.ts
@@ -0,0 +1,20 @@
+/*
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import { AppExtension } from '../../base/app-extension'
+import type { MarkdownRendererExtension } from '../../../components/markdown-renderer/extensions/base/markdown-renderer-extension'
+import { SpoilerMarkdownExtension } from './spoiler-markdown-extension'
+
+/**
+ * Adds support for html spoiler tags.
+ *
+ * @see https://www.w3schools.com/tags/tag_details.asp
+ */
+export class SpoilerAppExtension extends AppExtension {
+  buildMarkdownRendererExtensions(): MarkdownRendererExtension[] {
+    return [new SpoilerMarkdownExtension()]
+  }
+}
diff --git a/src/components/markdown-renderer/markdown-extension/spoiler-markdown-extension.ts b/src/extensions/extra-integrations/spoiler/spoiler-markdown-extension.ts
similarity index 84%
rename from src/components/markdown-renderer/markdown-extension/spoiler-markdown-extension.ts
rename to src/extensions/extra-integrations/spoiler/spoiler-markdown-extension.ts
index 5509a49e5..7b96a23e0 100644
--- a/src/components/markdown-renderer/markdown-extension/spoiler-markdown-extension.ts
+++ b/src/extensions/extra-integrations/spoiler/spoiler-markdown-extension.ts
@@ -4,18 +4,18 @@
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
-import { MarkdownExtension } from './markdown-extension'
 import type MarkdownIt from 'markdown-it'
 import markdownItContainer from 'markdown-it-container'
 import type Token from 'markdown-it/lib/token'
 import { escapeHtml } from 'markdown-it/lib/common/utils'
+import { MarkdownRendererExtension } from '../../../components/markdown-renderer/extensions/base/markdown-renderer-extension'
 
 /**
  * Adds support for html spoiler tags.
  *
  * @see https://www.w3schools.com/tags/tag_details.asp
  */
-export class SpoilerMarkdownExtension extends MarkdownExtension {
+export class SpoilerMarkdownExtension extends MarkdownRendererExtension {
   private static readonly spoilerRegEx = /^spoiler\s+(.*)$/
 
   private static renderSpoilerContainer(tokens: Token[], index: number): string {
diff --git a/src/extensions/extra-integrations/task-list/event-emitting-task-list-checkbox.tsx b/src/extensions/extra-integrations/task-list/event-emitting-task-list-checkbox.tsx
new file mode 100644
index 000000000..5356ac9cb
--- /dev/null
+++ b/src/extensions/extra-integrations/task-list/event-emitting-task-list-checkbox.tsx
@@ -0,0 +1,35 @@
+/*
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import React, { useCallback } from 'react'
+import type { TaskCheckedChangeHandler, TaskListProps } from './task-list-checkbox'
+import { TaskListCheckbox } from './task-list-checkbox'
+import { useExtensionEventEmitter } from '../../../components/markdown-renderer/hooks/use-extension-event-emitter'
+import { TaskListCheckboxAppExtension } from './task-list-checkbox-app-extension'
+
+type EventEmittingTaskListCheckboxProps = Omit<TaskListProps, 'onTaskCheckedChange' | 'disabled'>
+
+export interface TaskCheckedEventPayload {
+  lineInMarkdown: number
+  checked: boolean
+}
+
+/**
+ * Wraps a {@link TaskListCheckbox} but sends state changes to the current {@link EventEmitter2 event emitter}.
+ *
+ * @param props Props that will be forwarded to the checkbox.
+ */
+export const EventEmittingTaskListCheckbox: React.FC<EventEmittingTaskListCheckboxProps> = (props) => {
+  const emitter = useExtensionEventEmitter()
+  const sendEvent: TaskCheckedChangeHandler = useCallback(
+    (lineInMarkdown: number, checked: boolean) => {
+      emitter?.emit(TaskListCheckboxAppExtension.EVENT_NAME, { lineInMarkdown, checked } as TaskCheckedEventPayload)
+    },
+    [emitter]
+  )
+
+  return <TaskListCheckbox onTaskCheckedChange={sendEvent} disabled={emitter === undefined} {...props} />
+}
diff --git a/src/extensions/extra-integrations/task-list/set-checkbox-in-editor.tsx b/src/extensions/extra-integrations/task-list/set-checkbox-in-editor.tsx
new file mode 100644
index 000000000..32de0eeee
--- /dev/null
+++ b/src/extensions/extra-integrations/task-list/set-checkbox-in-editor.tsx
@@ -0,0 +1,19 @@
+/*
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import type React from 'react'
+import { useSetCheckboxInEditor } from './use-set-checkbox-in-editor'
+import { useExtensionEventEmitterHandler } from '../../../components/markdown-renderer/hooks/use-extension-event-emitter'
+import { TaskListCheckboxAppExtension } from './task-list-checkbox-app-extension'
+
+/**
+ * Receives task-checkbox-change events and modify the current editor content.
+ */
+export const SetCheckboxInEditor: React.FC = () => {
+  const changeCallback = useSetCheckboxInEditor()
+  useExtensionEventEmitterHandler(TaskListCheckboxAppExtension.EVENT_NAME, changeCallback)
+  return null
+}
diff --git a/src/extensions/extra-integrations/task-list/task-list-checkbox-app-extension.ts b/src/extensions/extra-integrations/task-list/task-list-checkbox-app-extension.ts
new file mode 100644
index 000000000..bbe003956
--- /dev/null
+++ b/src/extensions/extra-integrations/task-list/task-list-checkbox-app-extension.ts
@@ -0,0 +1,26 @@
+/*
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import type EventEmitter2 from 'eventemitter2'
+import { AppExtension } from '../../base/app-extension'
+import { TaskListMarkdownExtension } from './task-list-markdown-extension'
+import type React from 'react'
+import { SetCheckboxInEditor } from './set-checkbox-in-editor'
+
+/**
+ * Adds support for interactive checkbox lists to the markdown renderer.
+ */
+export class TaskListCheckboxAppExtension extends AppExtension {
+  public static readonly EVENT_NAME = 'TaskListCheckbox'
+
+  buildMarkdownRendererExtensions(eventEmitter: EventEmitter2): TaskListMarkdownExtension[] {
+    return [new TaskListMarkdownExtension(eventEmitter)]
+  }
+
+  buildEditorExtensionComponent(): React.FC {
+    return SetCheckboxInEditor
+  }
+}
diff --git a/src/components/markdown-renderer/markdown-extension/task-list/task-list-checkbox.tsx b/src/extensions/extra-integrations/task-list/task-list-checkbox.tsx
similarity index 62%
rename from src/components/markdown-renderer/markdown-extension/task-list/task-list-checkbox.tsx
rename to src/extensions/extra-integrations/task-list/task-list-checkbox.tsx
index 678dd67ed..e233fff72 100644
--- a/src/components/markdown-renderer/markdown-extension/task-list/task-list-checkbox.tsx
+++ b/src/extensions/extra-integrations/task-list/task-list-checkbox.tsx
@@ -1,15 +1,18 @@
 /*
- * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
  *
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
 import React, { useCallback } from 'react'
 
+export type TaskCheckedChangeHandler = (lineInMarkdown: number, checked: boolean) => void
+
 export interface TaskListProps {
-  onTaskCheckedChange?: (lineInMarkdown: number, checked: boolean) => void
+  onTaskCheckedChange?: TaskCheckedChangeHandler
   checked: boolean
   lineInMarkdown?: number
+  disabled?: boolean
 }
 
 /**
@@ -19,19 +22,24 @@ export interface TaskListProps {
  * @param checked Determines if the checkbox should be rendered as checked
  * @param lineInMarkdown Defines the line in the markdown code this checkbox is mapped to. The information is send with the onTaskCheckedChange callback.
  */
-export const TaskListCheckbox: React.FC<TaskListProps> = ({ onTaskCheckedChange, checked, lineInMarkdown }) => {
+export const TaskListCheckbox: React.FC<TaskListProps> = ({
+  onTaskCheckedChange,
+  checked,
+  lineInMarkdown,
+  disabled
+}) => {
   const onChange = useCallback(
     (event: React.ChangeEvent<HTMLInputElement>): void => {
-      if (onTaskCheckedChange && lineInMarkdown !== undefined) {
+      if (onTaskCheckedChange && disabled !== true && lineInMarkdown !== undefined) {
         onTaskCheckedChange(lineInMarkdown, event.currentTarget.checked)
       }
     },
-    [lineInMarkdown, onTaskCheckedChange]
+    [disabled, lineInMarkdown, onTaskCheckedChange]
   )
 
   return (
     <input
-      disabled={onTaskCheckedChange === undefined}
+      disabled={disabled !== true && onTaskCheckedChange === undefined}
       className='task-list-item-checkbox'
       type='checkbox'
       checked={checked}
diff --git a/src/components/markdown-renderer/markdown-extension/task-list/task-list-markdown-extension.ts b/src/extensions/extra-integrations/task-list/task-list-markdown-extension.ts
similarity index 53%
rename from src/components/markdown-renderer/markdown-extension/task-list/task-list-markdown-extension.ts
rename to src/extensions/extra-integrations/task-list/task-list-markdown-extension.ts
index 4f8a89ca8..7e08c2acd 100644
--- a/src/components/markdown-renderer/markdown-extension/task-list/task-list-markdown-extension.ts
+++ b/src/extensions/extra-integrations/task-list/task-list-markdown-extension.ts
@@ -1,24 +1,19 @@
 /*
- * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
  *
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
-import { MarkdownExtension } from '../markdown-extension'
 import type MarkdownIt from 'markdown-it'
-import type { ComponentReplacer } from '../../replace-components/component-replacer'
-import type { TaskCheckedChangeHandler } from './task-list-replacer'
 import { TaskListReplacer } from './task-list-replacer'
 import markdownItTaskLists from '@hedgedoc/markdown-it-task-lists'
+import type { ComponentReplacer } from '../../../components/markdown-renderer/replace-components/component-replacer'
+import { MarkdownRendererExtension } from '../../../components/markdown-renderer/extensions/base/markdown-renderer-extension'
 
 /**
  * Adds support for interactive checkbox lists to the markdown rendering using the github checklist syntax.
  */
-export class TaskListMarkdownExtension extends MarkdownExtension {
-  constructor(private onTaskCheckedChange?: TaskCheckedChangeHandler) {
-    super()
-  }
-
+export class TaskListMarkdownExtension extends MarkdownRendererExtension {
   public configureMarkdownIt(markdownIt: MarkdownIt): void {
     markdownItTaskLists(markdownIt, {
       enabled: true,
@@ -28,6 +23,6 @@ export class TaskListMarkdownExtension extends MarkdownExtension {
   }
 
   public buildReplacers(): ComponentReplacer[] {
-    return [new TaskListReplacer(this.onTaskCheckedChange)]
+    return [new TaskListReplacer()]
   }
 }
diff --git a/src/extensions/extra-integrations/task-list/task-list-replacer.tsx b/src/extensions/extra-integrations/task-list/task-list-replacer.tsx
new file mode 100644
index 000000000..70a7a536f
--- /dev/null
+++ b/src/extensions/extra-integrations/task-list/task-list-replacer.tsx
@@ -0,0 +1,31 @@
+/*
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import type { Element } from 'domhandler'
+import React from 'react'
+import type { NodeReplacement } from '../../../components/markdown-renderer/replace-components/component-replacer'
+import {
+  ComponentReplacer,
+  DO_NOT_REPLACE
+} from '../../../components/markdown-renderer/replace-components/component-replacer'
+import { EventEmittingTaskListCheckbox } from './event-emitting-task-list-checkbox'
+
+/**
+ * Detects task lists and renders them as checkboxes that execute a callback if clicked.
+ */
+export class TaskListReplacer extends ComponentReplacer {
+  public replace(node: Element): NodeReplacement {
+    if (node.attribs?.class !== 'task-list-item-checkbox') {
+      return DO_NOT_REPLACE
+    }
+    const lineInMarkdown = Number(node.attribs['data-line'])
+    return isNaN(lineInMarkdown) ? (
+      DO_NOT_REPLACE
+    ) : (
+      <EventEmittingTaskListCheckbox checked={node.attribs.checked !== undefined} lineInMarkdown={lineInMarkdown} />
+    )
+  }
+}
diff --git a/src/components/editor-page/editor-document-renderer/hooks/use-set-checkbox-in-editor.tsx b/src/extensions/extra-integrations/task-list/use-set-checkbox-in-editor.tsx
similarity index 76%
rename from src/components/editor-page/editor-document-renderer/hooks/use-set-checkbox-in-editor.tsx
rename to src/extensions/extra-integrations/task-list/use-set-checkbox-in-editor.tsx
index cab977341..4a4582dcb 100644
--- a/src/components/editor-page/editor-document-renderer/hooks/use-set-checkbox-in-editor.tsx
+++ b/src/extensions/extra-integrations/task-list/use-set-checkbox-in-editor.tsx
@@ -4,10 +4,12 @@
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
-import { useChangeEditorContentCallback } from '../../change-content-context/use-change-editor-content-callback'
 import { useCallback } from 'react'
-import type { ContentEdits } from '../../editor-pane/tool-bar/formatters/types/changes'
 import { Optional } from '@mrdrogdrog/optional'
+import { useChangeEditorContentCallback } from '../../../components/editor-page/change-content-context/use-change-editor-content-callback'
+import type { ContentEdits } from '../../../components/editor-page/editor-pane/tool-bar/formatters/types/changes'
+import type { TaskCheckedEventPayload } from './event-emitting-task-list-checkbox'
+import { store } from '../../../redux'
 
 const TASK_REGEX = /(\s*(?:[-*+]|\d+[.)]) )(\[[ xX]?])/
 
@@ -18,14 +20,15 @@ export const useSetCheckboxInEditor = () => {
   const changeEditorContent = useChangeEditorContentCallback()
 
   return useCallback(
-    (changedLineIndex: number, checkboxChecked: boolean): void => {
+    ({ lineInMarkdown, checked }: TaskCheckedEventPayload): void => {
       changeEditorContent?.(({ markdownContent }) => {
         const lines = markdownContent.split('\n')
-        const lineStartIndex = findStartIndexOfLine(lines, changedLineIndex)
-        const edits = Optional.ofNullable(TASK_REGEX.exec(lines[changedLineIndex]))
+        const correctedLineIndex = lineInMarkdown + store.getState().noteDetails.frontmatterRendererInfo.lineOffset
+        const lineStartIndex = findStartIndexOfLine(lines, correctedLineIndex)
+        const edits = Optional.ofNullable(TASK_REGEX.exec(lines[correctedLineIndex]))
           .map(([, beforeCheckbox, oldCheckbox]) => {
             const checkboxStartIndex = lineStartIndex + beforeCheckbox.length
-            return createCheckboxContentEdit(checkboxStartIndex, oldCheckbox, checkboxChecked)
+            return createCheckboxContentEdit(checkboxStartIndex, oldCheckbox, checked)
           })
           .orElse([])
         return [edits, undefined]
diff --git a/src/components/markdown-renderer/markdown-extension/vega-lite/__snapshots__/vega-lite-markdown-extension.test.tsx.snap b/src/extensions/extra-integrations/vega-lite/__snapshots__/vega-lite-markdown-extension.test.tsx.snap
similarity index 100%
rename from src/components/markdown-renderer/markdown-extension/vega-lite/__snapshots__/vega-lite-markdown-extension.test.tsx.snap
rename to src/extensions/extra-integrations/vega-lite/__snapshots__/vega-lite-markdown-extension.test.tsx.snap
diff --git a/src/extensions/extra-integrations/vega-lite/vega-lite-app-extension.ts b/src/extensions/extra-integrations/vega-lite/vega-lite-app-extension.ts
new file mode 100644
index 000000000..9a8b7748d
--- /dev/null
+++ b/src/extensions/extra-integrations/vega-lite/vega-lite-app-extension.ts
@@ -0,0 +1,18 @@
+/*
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import { AppExtension } from '../../base/app-extension'
+import type { MarkdownRendererExtension } from '../../../components/markdown-renderer/extensions/base/markdown-renderer-extension'
+import { VegaLiteMarkdownExtension } from './vega-lite-markdown-extension'
+
+/**
+ * Adds support for chart rendering using vega lite to the markdown renderer.
+ */
+export class VegaLiteAppExtension extends AppExtension {
+  buildMarkdownRendererExtensions(): MarkdownRendererExtension[] {
+    return [new VegaLiteMarkdownExtension()]
+  }
+}
diff --git a/src/components/markdown-renderer/markdown-extension/vega-lite/vega-lite-chart.tsx b/src/extensions/extra-integrations/vega-lite/vega-lite-chart.tsx
similarity index 85%
rename from src/components/markdown-renderer/markdown-extension/vega-lite/vega-lite-chart.tsx
rename to src/extensions/extra-integrations/vega-lite/vega-lite-chart.tsx
index 77bf02e72..5823b0930 100644
--- a/src/components/markdown-renderer/markdown-extension/vega-lite/vega-lite-chart.tsx
+++ b/src/extensions/extra-integrations/vega-lite/vega-lite-chart.tsx
@@ -8,11 +8,11 @@ import React, { useEffect, useRef } from 'react'
 import { Alert } from 'react-bootstrap'
 import { Trans, useTranslation } from 'react-i18next'
 import type { VisualizationSpec } from 'vega-embed'
-import { ShowIf } from '../../../common/show-if/show-if'
-import { Logger } from '../../../../utils/logger'
-import type { CodeProps } from '../../replace-components/code-block-component-replacer'
 import { useAsync } from 'react-use'
-import { AsyncLoadingBoundary } from '../../../common/async-loading-boundary'
+import type { CodeProps } from '../../../components/markdown-renderer/replace-components/code-block-component-replacer'
+import { AsyncLoadingBoundary } from '../../../components/common/async-loading-boundary'
+import { ShowIf } from '../../../components/common/show-if/show-if'
+import { Logger } from '../../../utils/logger'
 
 const log = new Logger('VegaChart')
 
diff --git a/src/components/markdown-renderer/markdown-extension/vega-lite/vega-lite-markdown-extension.test.tsx b/src/extensions/extra-integrations/vega-lite/vega-lite-markdown-extension.test.tsx
similarity index 78%
rename from src/components/markdown-renderer/markdown-extension/vega-lite/vega-lite-markdown-extension.test.tsx
rename to src/extensions/extra-integrations/vega-lite/vega-lite-markdown-extension.test.tsx
index 5bb54a9b5..2ca055a4f 100644
--- a/src/components/markdown-renderer/markdown-extension/vega-lite/vega-lite-markdown-extension.test.tsx
+++ b/src/extensions/extra-integrations/vega-lite/vega-lite-markdown-extension.test.tsx
@@ -5,12 +5,12 @@
  */
 
 import { render } from '@testing-library/react'
-import { TestMarkdownRenderer } from '../../test-utils/test-markdown-renderer'
 import React from 'react'
-import { mockI18n } from '../../test-utils/mock-i18n'
 import { VegaLiteMarkdownExtension } from './vega-lite-markdown-extension'
 import * as VegaLiteChartModule from '../vega-lite/vega-lite-chart'
-import type { CodeProps } from '../../replace-components/code-block-component-replacer'
+import { mockI18n } from '../../../components/markdown-renderer/test-utils/mock-i18n'
+import type { CodeProps } from '../../../components/markdown-renderer/replace-components/code-block-component-replacer'
+import { TestMarkdownRenderer } from '../../../components/markdown-renderer/test-utils/test-markdown-renderer'
 
 jest.mock('../vega-lite/vega-lite-chart')
 
diff --git a/src/extensions/extra-integrations/vega-lite/vega-lite-markdown-extension.ts b/src/extensions/extra-integrations/vega-lite/vega-lite-markdown-extension.ts
new file mode 100644
index 000000000..1ed060e42
--- /dev/null
+++ b/src/extensions/extra-integrations/vega-lite/vega-lite-markdown-extension.ts
@@ -0,0 +1,18 @@
+/*
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import { VegaLiteChart } from './vega-lite-chart'
+import { CodeBlockMarkdownRendererExtension } from '../../../components/markdown-renderer/extensions/base/code-block-markdown-extension/code-block-markdown-renderer-extension'
+import { CodeBlockComponentReplacer } from '../../../components/markdown-renderer/replace-components/code-block-component-replacer'
+
+/**
+ * Adds support for chart rendering using vega lite to the markdown rendering using code fences with "vega-lite" as language.
+ */
+export class VegaLiteMarkdownExtension extends CodeBlockMarkdownRendererExtension {
+  public buildReplacers(): CodeBlockComponentReplacer[] {
+    return [new CodeBlockComponentReplacer(VegaLiteChart, 'vega-lite')]
+  }
+}
diff --git a/src/components/markdown-renderer/markdown-extension/vimeo/__snapshots__/vimeo-frame.test.tsx.snap b/src/extensions/extra-integrations/vimeo/__snapshots__/vimeo-frame.test.tsx.snap
similarity index 100%
rename from src/components/markdown-renderer/markdown-extension/vimeo/__snapshots__/vimeo-frame.test.tsx.snap
rename to src/extensions/extra-integrations/vimeo/__snapshots__/vimeo-frame.test.tsx.snap
diff --git a/src/components/markdown-renderer/markdown-extension/vimeo/replace-legacy-vimeo-short-code.test.ts b/src/extensions/extra-integrations/vimeo/replace-legacy-vimeo-short-code.test.ts
similarity index 100%
rename from src/components/markdown-renderer/markdown-extension/vimeo/replace-legacy-vimeo-short-code.test.ts
rename to src/extensions/extra-integrations/vimeo/replace-legacy-vimeo-short-code.test.ts
diff --git a/src/components/markdown-renderer/markdown-extension/vimeo/replace-legacy-vimeo-short-code.ts b/src/extensions/extra-integrations/vimeo/replace-legacy-vimeo-short-code.ts
similarity index 92%
rename from src/components/markdown-renderer/markdown-extension/vimeo/replace-legacy-vimeo-short-code.ts
rename to src/extensions/extra-integrations/vimeo/replace-legacy-vimeo-short-code.ts
index 5ce9a4c2c..4b3511cf7 100644
--- a/src/components/markdown-renderer/markdown-extension/vimeo/replace-legacy-vimeo-short-code.ts
+++ b/src/extensions/extra-integrations/vimeo/replace-legacy-vimeo-short-code.ts
@@ -4,10 +4,10 @@
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
-import type { RegexOptions } from '../../../../external-types/markdown-it-regex/interface'
 import { VimeoMarkdownExtension } from './vimeo-markdown-extension'
 import type MarkdownIt from 'markdown-it'
 import markdownItRegex from 'markdown-it-regex'
+import type { RegexOptions } from '../../../external-types/markdown-it-regex/interface'
 
 export const legacyVimeoRegex = /^{%vimeo\s+(\d{6,11})\s*%}$/
 
diff --git a/src/components/markdown-renderer/markdown-extension/vimeo/replace-vimeo-link.test.ts b/src/extensions/extra-integrations/vimeo/replace-vimeo-link.test.ts
similarity index 100%
rename from src/components/markdown-renderer/markdown-extension/vimeo/replace-vimeo-link.test.ts
rename to src/extensions/extra-integrations/vimeo/replace-vimeo-link.test.ts
diff --git a/src/components/markdown-renderer/markdown-extension/vimeo/replace-vimeo-link.ts b/src/extensions/extra-integrations/vimeo/replace-vimeo-link.ts
similarity index 93%
rename from src/components/markdown-renderer/markdown-extension/vimeo/replace-vimeo-link.ts
rename to src/extensions/extra-integrations/vimeo/replace-vimeo-link.ts
index d4245dae3..98c7fc22e 100644
--- a/src/components/markdown-renderer/markdown-extension/vimeo/replace-vimeo-link.ts
+++ b/src/extensions/extra-integrations/vimeo/replace-vimeo-link.ts
@@ -4,10 +4,10 @@
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
-import type { RegexOptions } from '../../../../external-types/markdown-it-regex/interface'
 import { VimeoMarkdownExtension } from './vimeo-markdown-extension'
 import type MarkdownIt from 'markdown-it'
 import markdownItRegex from 'markdown-it-regex'
+import type { RegexOptions } from '../../../external-types/markdown-it-regex/interface'
 
 const protocolRegex = /(?:http(?:s)?:\/\/)?/
 const domainRegex = /(?:player\.)?(?:vimeo\.com\/)(?:(?:channels|album|ondemand|groups)\/\w+\/)?(?:video\/)?/
diff --git a/src/extensions/extra-integrations/vimeo/vimeo-app-extension.ts b/src/extensions/extra-integrations/vimeo/vimeo-app-extension.ts
new file mode 100644
index 000000000..d7ad11d72
--- /dev/null
+++ b/src/extensions/extra-integrations/vimeo/vimeo-app-extension.ts
@@ -0,0 +1,32 @@
+/*
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import { AppExtension } from '../../base/app-extension'
+import type { MarkdownRendererExtension } from '../../../components/markdown-renderer/extensions/base/markdown-renderer-extension'
+import { VimeoMarkdownExtension } from './vimeo-markdown-extension'
+import type { Linter } from '../../../components/editor-page/editor-pane/linter/linter'
+import { SingleLineRegexLinter } from '../../../components/editor-page/editor-pane/linter/single-line-regex-linter'
+import { legacyVimeoRegex } from './replace-legacy-vimeo-short-code'
+import { t } from 'i18next'
+
+/**
+ * Adds vimeo video embeddings to the markdown renderer.
+ */
+export class VimeoAppExtension extends AppExtension {
+  buildMarkdownRendererExtensions(): MarkdownRendererExtension[] {
+    return [new VimeoMarkdownExtension()]
+  }
+
+  buildCodeMirrorLinter(): Linter[] {
+    return [
+      new SingleLineRegexLinter(
+        legacyVimeoRegex,
+        t('editor.linter.shortcode', { shortcode: 'Vimeo' }),
+        (match: string) => `https://player.vimeo.com/video/${match}`
+      )
+    ]
+  }
+}
diff --git a/src/components/markdown-renderer/markdown-extension/vimeo/vimeo-frame.test.tsx b/src/extensions/extra-integrations/vimeo/vimeo-frame.test.tsx
similarity index 65%
rename from src/components/markdown-renderer/markdown-extension/vimeo/vimeo-frame.test.tsx
rename to src/extensions/extra-integrations/vimeo/vimeo-frame.test.tsx
index 1a12c5059..f9d642afb 100644
--- a/src/components/markdown-renderer/markdown-extension/vimeo/vimeo-frame.test.tsx
+++ b/src/extensions/extra-integrations/vimeo/vimeo-frame.test.tsx
@@ -6,10 +6,10 @@
 import { render } from '@testing-library/react'
 import { VimeoFrame } from './vimeo-frame'
 import React from 'react'
-import type { ClickShieldProps } from '../../replace-components/click-shield/click-shield'
-import * as ClickShieldModule from '../../replace-components/click-shield/click-shield'
+import * as ClickShieldModule from '../../../components/markdown-renderer/replace-components/click-shield/click-shield'
+import type { ClickShieldProps } from '../../../components/markdown-renderer/replace-components/click-shield/click-shield'
 
-jest.mock('../../replace-components/click-shield/click-shield')
+jest.mock('../../../components/markdown-renderer/replace-components/click-shield/click-shield')
 
 describe('VimeoFrame', () => {
   beforeEach(() => {
diff --git a/src/components/markdown-renderer/markdown-extension/vimeo/vimeo-frame.tsx b/src/extensions/extra-integrations/vimeo/vimeo-frame.tsx
similarity index 84%
rename from src/components/markdown-renderer/markdown-extension/vimeo/vimeo-frame.tsx
rename to src/extensions/extra-integrations/vimeo/vimeo-frame.tsx
index 095cb97f8..f839c19a8 100644
--- a/src/components/markdown-renderer/markdown-extension/vimeo/vimeo-frame.tsx
+++ b/src/extensions/extra-integrations/vimeo/vimeo-frame.tsx
@@ -1,12 +1,12 @@
 /*
- * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
  *
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
 import React, { useCallback } from 'react'
-import type { IdProps } from '../../replace-components/custom-tag-with-id-component-replacer'
-import { ClickShield } from '../../replace-components/click-shield/click-shield'
+import { ClickShield } from '../../../components/markdown-renderer/replace-components/click-shield/click-shield'
+import type { IdProps } from '../../../components/markdown-renderer/replace-components/custom-tag-with-id-component-replacer'
 
 interface VimeoApiResponse {
   // Vimeo uses strange names for their fields. ESLint doesn't like that.
diff --git a/src/extensions/extra-integrations/vimeo/vimeo-markdown-extension.ts b/src/extensions/extra-integrations/vimeo/vimeo-markdown-extension.ts
new file mode 100644
index 000000000..f8466dbee
--- /dev/null
+++ b/src/extensions/extra-integrations/vimeo/vimeo-markdown-extension.ts
@@ -0,0 +1,33 @@
+/*
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import type MarkdownIt from 'markdown-it'
+import { replaceVimeoLinkMarkdownItPlugin } from './replace-vimeo-link'
+import { VimeoFrame } from './vimeo-frame'
+import { replaceLegacyVimeoShortCodeMarkdownItPlugin } from './replace-legacy-vimeo-short-code'
+import type { ComponentReplacer } from '../../../components/markdown-renderer/replace-components/component-replacer'
+import { MarkdownRendererExtension } from '../../../components/markdown-renderer/extensions/base/markdown-renderer-extension'
+import { CustomTagWithIdComponentReplacer } from '../../../components/markdown-renderer/replace-components/custom-tag-with-id-component-replacer'
+
+/**
+ * Adds vimeo video embeddings using link detection and the legacy vimeo short code syntax.
+ */
+export class VimeoMarkdownExtension extends MarkdownRendererExtension {
+  public static readonly tagName = 'app-vimeo'
+
+  public configureMarkdownIt(markdownIt: MarkdownIt): void {
+    replaceLegacyVimeoShortCodeMarkdownItPlugin(markdownIt)
+    replaceVimeoLinkMarkdownItPlugin(markdownIt)
+  }
+
+  public buildReplacers(): ComponentReplacer[] {
+    return [new CustomTagWithIdComponentReplacer(VimeoFrame, VimeoMarkdownExtension.tagName)]
+  }
+
+  public buildTagNameAllowList(): string[] {
+    return [VimeoMarkdownExtension.tagName]
+  }
+}
diff --git a/src/components/markdown-renderer/markdown-extension/youtube/__snapshots__/youtube-frame.test.tsx.snap b/src/extensions/extra-integrations/youtube/__snapshots__/youtube-frame.test.tsx.snap
similarity index 100%
rename from src/components/markdown-renderer/markdown-extension/youtube/__snapshots__/youtube-frame.test.tsx.snap
rename to src/extensions/extra-integrations/youtube/__snapshots__/youtube-frame.test.tsx.snap
diff --git a/src/components/markdown-renderer/markdown-extension/youtube/__snapshots__/youtube-markdown-extension.test.tsx.snap b/src/extensions/extra-integrations/youtube/__snapshots__/youtube-markdown-extension.test.tsx.snap
similarity index 100%
rename from src/components/markdown-renderer/markdown-extension/youtube/__snapshots__/youtube-markdown-extension.test.tsx.snap
rename to src/extensions/extra-integrations/youtube/__snapshots__/youtube-markdown-extension.test.tsx.snap
diff --git a/src/components/markdown-renderer/markdown-extension/youtube/replace-legacy-youtube-short-code.test.ts b/src/extensions/extra-integrations/youtube/replace-legacy-youtube-short-code.test.ts
similarity index 100%
rename from src/components/markdown-renderer/markdown-extension/youtube/replace-legacy-youtube-short-code.test.ts
rename to src/extensions/extra-integrations/youtube/replace-legacy-youtube-short-code.test.ts
diff --git a/src/components/markdown-renderer/markdown-extension/youtube/replace-legacy-youtube-short-code.ts b/src/extensions/extra-integrations/youtube/replace-legacy-youtube-short-code.ts
similarity index 91%
rename from src/components/markdown-renderer/markdown-extension/youtube/replace-legacy-youtube-short-code.ts
rename to src/extensions/extra-integrations/youtube/replace-legacy-youtube-short-code.ts
index 574b75f93..e73b3e7e8 100644
--- a/src/components/markdown-renderer/markdown-extension/youtube/replace-legacy-youtube-short-code.ts
+++ b/src/extensions/extra-integrations/youtube/replace-legacy-youtube-short-code.ts
@@ -4,10 +4,10 @@
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
-import type { RegexOptions } from '../../../../external-types/markdown-it-regex/interface'
 import { YoutubeMarkdownExtension } from './youtube-markdown-extension'
 import markdownItRegex from 'markdown-it-regex'
 import type MarkdownIt from 'markdown-it'
+import type { RegexOptions } from '../../../external-types/markdown-it-regex/interface'
 
 export const legacyYouTubeRegex = /^{%youtube\s+([\w-]{11})\s*%}$/
 
diff --git a/src/components/markdown-renderer/markdown-extension/youtube/replace-youtube-link.test.ts b/src/extensions/extra-integrations/youtube/replace-youtube-link.test.ts
similarity index 100%
rename from src/components/markdown-renderer/markdown-extension/youtube/replace-youtube-link.test.ts
rename to src/extensions/extra-integrations/youtube/replace-youtube-link.test.ts
diff --git a/src/components/markdown-renderer/markdown-extension/youtube/replace-youtube-link.ts b/src/extensions/extra-integrations/youtube/replace-youtube-link.ts
similarity index 93%
rename from src/components/markdown-renderer/markdown-extension/youtube/replace-youtube-link.ts
rename to src/extensions/extra-integrations/youtube/replace-youtube-link.ts
index ffd92ecd8..0899e0e41 100644
--- a/src/components/markdown-renderer/markdown-extension/youtube/replace-youtube-link.ts
+++ b/src/extensions/extra-integrations/youtube/replace-youtube-link.ts
@@ -4,10 +4,10 @@
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
-import type { RegexOptions } from '../../../../external-types/markdown-it-regex/interface'
 import { YoutubeMarkdownExtension } from './youtube-markdown-extension'
 import markdownItRegex from 'markdown-it-regex'
 import type MarkdownIt from 'markdown-it'
+import type { RegexOptions } from '../../../external-types/markdown-it-regex/interface'
 
 const protocolRegex = /(?:http(?:s)?:\/\/)?/
 const subdomainRegex = /(?:www.)?/
diff --git a/src/extensions/extra-integrations/youtube/youtube-app-extension.ts b/src/extensions/extra-integrations/youtube/youtube-app-extension.ts
new file mode 100644
index 000000000..050b8dac5
--- /dev/null
+++ b/src/extensions/extra-integrations/youtube/youtube-app-extension.ts
@@ -0,0 +1,32 @@
+/*
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import { AppExtension } from '../../base/app-extension'
+import type { MarkdownRendererExtension } from '../../../components/markdown-renderer/extensions/base/markdown-renderer-extension'
+import { YoutubeMarkdownExtension } from './youtube-markdown-extension'
+import type { Linter } from '../../../components/editor-page/editor-pane/linter/linter'
+import { SingleLineRegexLinter } from '../../../components/editor-page/editor-pane/linter/single-line-regex-linter'
+import { legacyYouTubeRegex } from './replace-legacy-youtube-short-code'
+import { t } from 'i18next'
+
+/**
+ * Adds YouTube video embeddings to the markdown renderer.
+ */
+export class YoutubeAppExtension extends AppExtension {
+  buildMarkdownRendererExtensions(): MarkdownRendererExtension[] {
+    return [new YoutubeMarkdownExtension()]
+  }
+
+  public buildCodeMirrorLinter(): Linter[] {
+    return [
+      new SingleLineRegexLinter(
+        legacyYouTubeRegex,
+        t('editor.linter.shortcode', { shortcode: 'YouTube' }),
+        (match: string) => `https://www.youtube.com/watch?v=${match}`
+      )
+    ]
+  }
+}
diff --git a/src/components/markdown-renderer/markdown-extension/youtube/youtube-frame.test.tsx b/src/extensions/extra-integrations/youtube/youtube-frame.test.tsx
similarity index 66%
rename from src/components/markdown-renderer/markdown-extension/youtube/youtube-frame.test.tsx
rename to src/extensions/extra-integrations/youtube/youtube-frame.test.tsx
index 992e338b0..3eedbcd42 100644
--- a/src/components/markdown-renderer/markdown-extension/youtube/youtube-frame.test.tsx
+++ b/src/extensions/extra-integrations/youtube/youtube-frame.test.tsx
@@ -6,10 +6,10 @@
 import { render } from '@testing-library/react'
 import { YouTubeFrame } from './youtube-frame'
 import React from 'react'
-import type { ClickShieldProps } from '../../replace-components/click-shield/click-shield'
-import * as ClickShieldModule from '../../replace-components/click-shield/click-shield'
+import * as ClickShieldModule from '../../../components/markdown-renderer/replace-components/click-shield/click-shield'
+import type { ClickShieldProps } from '../../../components/markdown-renderer/replace-components/click-shield/click-shield'
 
-jest.mock('../../replace-components/click-shield/click-shield')
+jest.mock('../../../components/markdown-renderer/replace-components/click-shield/click-shield')
 
 describe('YoutubeFrame', () => {
   beforeEach(() => {
diff --git a/src/components/markdown-renderer/markdown-extension/youtube/youtube-frame.tsx b/src/extensions/extra-integrations/youtube/youtube-frame.tsx
similarity index 75%
rename from src/components/markdown-renderer/markdown-extension/youtube/youtube-frame.tsx
rename to src/extensions/extra-integrations/youtube/youtube-frame.tsx
index c80f710b8..0d36cddc4 100644
--- a/src/components/markdown-renderer/markdown-extension/youtube/youtube-frame.tsx
+++ b/src/extensions/extra-integrations/youtube/youtube-frame.tsx
@@ -1,12 +1,12 @@
 /*
- * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
  *
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
 import React from 'react'
-import type { IdProps } from '../../replace-components/custom-tag-with-id-component-replacer'
-import { ClickShield } from '../../replace-components/click-shield/click-shield'
+import { ClickShield } from '../../../components/markdown-renderer/replace-components/click-shield/click-shield'
+import type { IdProps } from '../../../components/markdown-renderer/replace-components/custom-tag-with-id-component-replacer'
 
 /**
  * Renders a video player embedding for https://youtube.com
diff --git a/src/components/markdown-renderer/markdown-extension/youtube/youtube-markdown-extension.test.tsx b/src/extensions/extra-integrations/youtube/youtube-markdown-extension.test.tsx
similarity index 82%
rename from src/components/markdown-renderer/markdown-extension/youtube/youtube-markdown-extension.test.tsx
rename to src/extensions/extra-integrations/youtube/youtube-markdown-extension.test.tsx
index fdca4b9e9..f64bf277c 100644
--- a/src/components/markdown-renderer/markdown-extension/youtube/youtube-markdown-extension.test.tsx
+++ b/src/extensions/extra-integrations/youtube/youtube-markdown-extension.test.tsx
@@ -6,11 +6,11 @@
 
 import { YoutubeMarkdownExtension } from './youtube-markdown-extension'
 import { render } from '@testing-library/react'
-import { TestMarkdownRenderer } from '../../test-utils/test-markdown-renderer'
 import * as YouTubeFrameModule from './youtube-frame'
 import React from 'react'
-import type { IdProps } from '../../replace-components/custom-tag-with-id-component-replacer'
-import { mockI18n } from '../../test-utils/mock-i18n'
+import { mockI18n } from '../../../components/markdown-renderer/test-utils/mock-i18n'
+import { TestMarkdownRenderer } from '../../../components/markdown-renderer/test-utils/test-markdown-renderer'
+import type { IdProps } from '../../../components/markdown-renderer/replace-components/custom-tag-with-id-component-replacer'
 
 jest.mock('./youtube-frame')
 
diff --git a/src/extensions/extra-integrations/youtube/youtube-markdown-extension.ts b/src/extensions/extra-integrations/youtube/youtube-markdown-extension.ts
new file mode 100644
index 000000000..1013e18ac
--- /dev/null
+++ b/src/extensions/extra-integrations/youtube/youtube-markdown-extension.ts
@@ -0,0 +1,33 @@
+/*
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import { replaceYouTubeLinkMarkdownItPlugin } from './replace-youtube-link'
+import { replaceLegacyYoutubeShortCodeMarkdownItPlugin } from './replace-legacy-youtube-short-code'
+import type MarkdownIt from 'markdown-it'
+import { YouTubeFrame } from './youtube-frame'
+import { MarkdownRendererExtension } from '../../../components/markdown-renderer/extensions/base/markdown-renderer-extension'
+import { CustomTagWithIdComponentReplacer } from '../../../components/markdown-renderer/replace-components/custom-tag-with-id-component-replacer'
+import type { ComponentReplacer } from '../../../components/markdown-renderer/replace-components/component-replacer'
+
+/**
+ * Adds YouTube video embeddings using link detection and the legacy YouTube short code syntax.
+ */
+export class YoutubeMarkdownExtension extends MarkdownRendererExtension {
+  public static readonly tagName = 'app-youtube'
+
+  public configureMarkdownIt(markdownIt: MarkdownIt): void {
+    replaceYouTubeLinkMarkdownItPlugin(markdownIt)
+    replaceLegacyYoutubeShortCodeMarkdownItPlugin(markdownIt)
+  }
+
+  public buildReplacers(): ComponentReplacer[] {
+    return [new CustomTagWithIdComponentReplacer(YouTubeFrame, YoutubeMarkdownExtension.tagName)]
+  }
+
+  public buildTagNameAllowList(): string[] {
+    return [YoutubeMarkdownExtension.tagName]
+  }
+}