diff --git a/services/web/scripts/create_backing_accounts_for_sl_users.js b/services/web/scripts/create_backing_accounts_for_sl_users.js
new file mode 100644
index 0000000000..457bf92030
--- /dev/null
+++ b/services/web/scripts/create_backing_accounts_for_sl_users.js
@@ -0,0 +1,83 @@
+/**
+ * create backing accounts for sl users without an overleaf.id
+ *
+ * run with:
+ * node scripts/create_backing_accounts_for_sl_users.js --async-limit=8 --commit
+ *
+ * async-limit is the number of concurrent users to process.
+ */
+
+'use strict'
+
+const SharelatexAuthHandler = require('../modules/overleaf-integration/app/js/SharelatexAuth/SharelatexAuthHandler')
+const UserUpdater = require('../app/js/Features/User/UserUpdater')
+const async = require('async')
+const { db } = require('../app/js/infrastructure/mongojs')
+const logger = require('logger-sharelatex')
+const minimist = require('minimist')
+
+logger.logger.level('error')
+
+const argv = minimist(process.argv.slice(2))
+const commit = argv.commit !== undefined
+const asyncLimit = parseInt(argv['async-limit']) || 1
+
+if (asyncLimit === 1) {
+  console.log(`running in series. run with --async-limit=n to run in parallel.`)
+}
+
+if (!commit) {
+  console.log(`doing dry run. run with --commit to save changes`)
+}
+
+const query = { 'overleaf.id': { $exists: false } }
+const projection = {
+  email: 1,
+  first_name: 1,
+  hashedPassword: 1,
+  last_name: 1
+}
+
+db.users.find(query, projection, (err, users) => {
+  if (err) throw err
+  async.eachLimit(users, asyncLimit, createBackingAccount, err => {
+    if (err) throw err
+    console.log('DONE')
+    process.exit()
+  })
+})
+
+function createBackingAccount(user, cb) {
+  console.log(
+    `Creating backing account for id: ${user._id}, email: ${user.email}`
+  )
+  if (!commit) return cb()
+  SharelatexAuthHandler.createBackingAccount(user, (err, v1Profile) => {
+    if (err) {
+      console.error(
+        `Error creating backing account for id: ${user._id}`,
+        err.stack
+      )
+      return cb()
+    }
+    console.log(
+      `Created backing account for id: ${user._id}, ol id: ${
+        v1Profile.id
+      } -- updating user`
+    )
+    const update = {
+      $set: {
+        'overleaf.id': v1Profile.id,
+        'ace.overallTheme': 'light-'
+      }
+    }
+    UserUpdater.updateUser(user._id, update, err => {
+      if (err) {
+        console.error(`Error updating user id: ${user._id}`, err.stack)
+        return cb()
+      }
+      console.log(`Updated user id: ${user._id}`)
+      cb()
+    })
+  })
+}