diff --git a/services/web/modules/user-activate/app/src/UserActivateController.js b/services/web/modules/user-activate/app/src/UserActivateController.mjs
similarity index 81%
rename from services/web/modules/user-activate/app/src/UserActivateController.js
rename to services/web/modules/user-activate/app/src/UserActivateController.mjs
index 5399a0cf6f..644fae42db 100644
--- a/services/web/modules/user-activate/app/src/UserActivateController.js
+++ b/services/web/modules/user-activate/app/src/UserActivateController.mjs
@@ -1,9 +1,12 @@
-const Path = require('path')
-const UserGetter = require('../../../../app/src/Features/User/UserGetter')
-const UserRegistrationHandler = require('../../../../app/src/Features/User/UserRegistrationHandler')
-const ErrorController = require('../../../../app/src/Features/Errors/ErrorController')
+import Path from 'node:path'
+import { fileURLToPath } from 'node:url'
+import UserGetter from '../../../../app/src/Features/User/UserGetter.js'
+import UserRegistrationHandler from '../../../../app/src/Features/User/UserRegistrationHandler.js'
+import ErrorController from '../../../../app/src/Features/Errors/ErrorController.js'
 
-module.exports = {
+const __dirname = Path.dirname(fileURLToPath(import.meta.url))
+
+export default {
   registerNewUser(req, res, next) {
     res.render(Path.resolve(__dirname, '../views/user/register'))
   },
diff --git a/services/web/modules/user-activate/app/src/UserActivateRouter.js b/services/web/modules/user-activate/app/src/UserActivateRouter.mjs
similarity index 65%
rename from services/web/modules/user-activate/app/src/UserActivateRouter.js
rename to services/web/modules/user-activate/app/src/UserActivateRouter.mjs
index a9088dd544..402d05c562 100644
--- a/services/web/modules/user-activate/app/src/UserActivateRouter.js
+++ b/services/web/modules/user-activate/app/src/UserActivateRouter.mjs
@@ -1,9 +1,9 @@
-const logger = require('@overleaf/logger')
-const UserActivateController = require('./UserActivateController')
-const AuthenticationController = require('../../../../app/src/Features/Authentication/AuthenticationController')
-const AuthorizationMiddleware = require('../../../../app/src/Features/Authorization/AuthorizationMiddleware')
+import logger from '@overleaf/logger'
+import UserActivateController from './UserActivateController.mjs'
+import AuthenticationController from '../../../../app/src/Features/Authentication/AuthenticationController.js'
+import AuthorizationMiddleware from '../../../../app/src/Features/Authorization/AuthorizationMiddleware.js'
 
-module.exports = {
+export default {
   apply(webRouter) {
     logger.debug({}, 'Init UserActivate router')
 
diff --git a/services/web/modules/user-activate/index.js b/services/web/modules/user-activate/index.mjs
similarity index 59%
rename from services/web/modules/user-activate/index.js
rename to services/web/modules/user-activate/index.mjs
index d6ef502eb8..ca87af1582 100644
--- a/services/web/modules/user-activate/index.js
+++ b/services/web/modules/user-activate/index.mjs
@@ -1,4 +1,4 @@
-const UserActivateRouter = require('./app/src/UserActivateRouter')
+import UserActivateRouter from './app/src/UserActivateRouter.mjs'
 
 /**
  * @import { WebModule } from "../../types/web-module"
@@ -9,4 +9,4 @@ const UserActivateModule = {
   router: UserActivateRouter,
 }
 
-module.exports = UserActivateModule
+export default UserActivateModule
diff --git a/services/web/modules/user-activate/test/unit/src/UserActivateControllerTests.js b/services/web/modules/user-activate/test/unit/src/UserActivateControllerTests.mjs
similarity index 83%
rename from services/web/modules/user-activate/test/unit/src/UserActivateControllerTests.js
rename to services/web/modules/user-activate/test/unit/src/UserActivateControllerTests.mjs
index 9259b48043..8e4f37e886 100644
--- a/services/web/modules/user-activate/test/unit/src/UserActivateControllerTests.js
+++ b/services/web/modules/user-activate/test/unit/src/UserActivateControllerTests.mjs
@@ -1,15 +1,16 @@
-const Path = require('path')
-const SandboxedModule = require('sandboxed-module')
-const sinon = require('sinon')
+import Path from 'node:path'
+import { fileURLToPath } from 'node:url'
+import { strict as esmock } from 'esmock'
+import sinon from 'sinon'
+
+const __dirname = Path.dirname(fileURLToPath(import.meta.url))
+
+const MODULE_PATH = '../../../app/src/UserActivateController.mjs'
 
-const MODULE_PATH = Path.join(
-  __dirname,
-  '../../../app/src/UserActivateController.js'
-)
 const VIEW_PATH = Path.join(__dirname, '../../../app/views/user/activate')
 
 describe('UserActivateController', function () {
-  beforeEach(function () {
+  beforeEach(async function () {
     this.user = {
       _id: (this.user_id = 'kwjewkl'),
       features: {},
@@ -19,14 +20,12 @@ describe('UserActivateController', function () {
     this.UserGetter = { getUser: sinon.stub() }
     this.UserRegistrationHandler = {}
     this.ErrorController = { notFound: sinon.stub() }
-    this.UserActivateController = SandboxedModule.require(MODULE_PATH, {
-      requires: {
-        '../../../../app/src/Features/User/UserGetter': this.UserGetter,
-        '../../../../app/src/Features/User/UserRegistrationHandler':
-          this.UserRegistrationHandler,
-        '../../../../app/src/Features/Errors/ErrorController':
-          this.ErrorController,
-      },
+    this.UserActivateController = await esmock(MODULE_PATH, {
+      '../../../../../app/src/Features/User/UserGetter.js': this.UserGetter,
+      '../../../../../app/src/Features/User/UserRegistrationHandler.js':
+        this.UserRegistrationHandler,
+      '../../../../../app/src/Features/Errors/ErrorController.js':
+        this.ErrorController,
     })
     this.req = {
       body: {},