diff --git a/services/history-v1/storage/scripts/redact.mjs b/services/history-v1/storage/scripts/redact.mjs
new file mode 100644
index 0000000000..3b63af8eb1
--- /dev/null
+++ b/services/history-v1/storage/scripts/redact.mjs
@@ -0,0 +1,144 @@
+import fs from 'node:fs'
+import { Readable } from 'node:stream'
+import { createRequire } from 'node:module'
+import * as readline from 'node:readline/promises'
+import commandLineArgs from 'command-line-args'
+import { makeProjectKey } from '../lib/blob_store/index.js'
+import { client } from '../lib/mongodb.js'
+import knex from '../lib/knex.js'
+import redis from '../lib/redis.js'
+
+const require = createRequire(import.meta.url)
+const config = require('config')
+const persistor = require('../lib/persistor.js')
+const { Errors } = require('@overleaf/object-persistor')
+
+const optionDefinitions = [
+  { name: 'historyId', alias: 'p', type: String },
+  { name: 'blob', alias: 'b', type: String },
+  { name: 'file', alias: 'f', type: String },
+  { name: 'empty', alias: 'e', type: Boolean },
+  { name: 'delete', alias: 'd', type: Boolean },
+  { name: 'yes', alias: 'y', type: Boolean },
+  { name: 'message', alias: 'm', type: String },
+]
+
+async function replaceBlob(historyId, blobHash, options) {
+  const bucket = config.get('blobStore.projectBucket')
+  const key = makeProjectKey(historyId, blobHash)
+
+  // 1. Check existence
+  let originalSize
+  try {
+    originalSize = await persistor.getObjectSize(bucket, key)
+    console.log(`Found blob ${blobHash} of size ${originalSize} bytes`)
+  } catch (err) {
+    if (
+      err instanceof Errors.NotFoundError ||
+      err.code === 'NoSuchKey' ||
+      err.name === 'NoSuchKey'
+    ) {
+      throw new Error(`Blob ${blobHash} not found in project ${historyId}`)
+    }
+    throw err
+  }
+
+  // 2. Prepare action
+  let stream
+  let streamSize
+  let actionDesc
+  if (!options.delete) {
+    if (options.empty) {
+      stream = Readable.from([])
+      streamSize = 0
+      actionDesc = 'empty file'
+    } else if (options.file) {
+      const stat = fs.statSync(options.file)
+      stream = fs.createReadStream(options.file)
+      streamSize = stat.size
+      actionDesc = `file ${options.file}`
+    } else {
+      const baseMessage = options.message || 'REDACTED'
+      const msg = `${baseMessage} ${new Date().toISOString()}`
+      const buf = Buffer.from(msg, 'utf8')
+      stream = Readable.from([buf])
+      streamSize = buf.length
+      actionDesc = `message "${msg}"`
+    }
+  }
+
+  const actionLog = options.delete
+    ? `Deleting blob ${blobHash} in ${historyId}`
+    : `Replacing blob ${blobHash} in ${historyId} with ${actionDesc} (${streamSize} bytes)`
+
+  console.log(actionLog)
+
+  if (!options.yes) {
+    const rl = readline.createInterface({
+      input: process.stdin,
+      output: process.stdout,
+    })
+    const answer = await rl.question('Proceed (Y/N)? ')
+    rl.close()
+    if (answer.toLowerCase() !== 'y') {
+      console.log('Aborted.')
+      return
+    }
+  }
+
+  // 3. Execute action
+  if (options.delete) {
+    await persistor.deleteObject(bucket, key)
+    console.log('Blob deleted successfully.')
+  } else {
+    await persistor.sendStream(bucket, key, stream, {
+      contentType: 'application/octet-stream',
+      contentLength: streamSize,
+    })
+    console.log('Blob replaced successfully.')
+  }
+}
+
+async function main() {
+  const options = commandLineArgs(optionDefinitions)
+  if (!options.historyId) {
+    console.error('Error: --historyId is required.')
+    process.exit(1)
+  }
+  if (!options.blob) {
+    console.error('Error: --blob is required.')
+    process.exit(1)
+  }
+
+  const activeModes = [
+    options.delete ? '--delete' : null,
+    options.empty ? '--empty' : null,
+    options.file ? '--file' : null,
+    options.message !== undefined ? '--message' : null,
+  ].filter(Boolean)
+
+  if (activeModes.length > 1) {
+    console.error(
+      `Error: Conflicting options provided (${activeModes.join(
+        ', '
+      )}). Please select exactly one redaction mode.`
+    )
+    process.exit(1)
+  }
+
+  await replaceBlob(options.historyId, options.blob, options)
+}
+
+main()
+  .then(() => console.log('Done.'))
+  .catch(err => {
+    console.error('Error:', err.message)
+    process.exit(1)
+  })
+  .finally(() => {
+    knex.destroy().catch(err => console.error('Error closing Postgres:', err))
+    client.close().catch(err => console.error('Error closing MongoDB:', err))
+    redis
+      .disconnect()
+      .catch(err => console.error('Error disconnecting Redis:', err))
+  })
diff --git a/services/history-v1/test/acceptance/js/storage/redact_blob.test.mjs b/services/history-v1/test/acceptance/js/storage/redact_blob.test.mjs
new file mode 100644
index 0000000000..10696e261a
--- /dev/null
+++ b/services/history-v1/test/acceptance/js/storage/redact_blob.test.mjs
@@ -0,0 +1,219 @@
+import { expect } from 'chai'
+import { promisify } from 'node:util'
+import { execFile } from 'node:child_process'
+import { ObjectId } from 'mongodb'
+
+import { BlobStore } from '../../../../storage/lib/blob_store/index.js'
+import cleanup from './support/cleanup.js'
+
+describe('redact.mjs script', function () {
+  const TIMEOUT = 20 * 1000
+
+  beforeEach(cleanup.everything)
+
+  async function runScript(args = []) {
+    let result
+    try {
+      result = await promisify(execFile)(
+        process.argv0,
+        ['storage/scripts/redact.mjs', ...args],
+        {
+          encoding: 'utf-8',
+          timeout: TIMEOUT,
+          env: {
+            ...process.env,
+            LOG_LEVEL: 'warn',
+          },
+        }
+      )
+      result.status = 0
+    } catch (err) {
+      const { stdout, stderr, code } = err
+      if (typeof code !== 'number') {
+        console.log(err)
+      }
+      result = { stdout, stderr, status: code }
+    }
+    return result
+  }
+
+  it('should redact one blob completely (via delete) and leave other unmodified', async function () {
+    const historyId = new ObjectId().toString()
+    const blobStore = new BlobStore(historyId)
+
+    const blob1 = await blobStore.putString('Confidential data')
+    const blob2 = await blobStore.putString('Public data')
+
+    const hash1 = blob1.getHash()
+    const hash2 = blob2.getHash()
+
+    // Redact blob1 completely
+    const result = await runScript([
+      '--historyId',
+      historyId,
+      '--blob',
+      hash1,
+      '--delete',
+      '--yes',
+    ])
+
+    expect(result.status).to.equal(0)
+    expect(result.stdout).to.include(`Deleting blob ${hash1}`)
+
+    // Check blob1 is absent using getStream (as getString can mask specific NotFoundError)
+    let fetchError
+    try {
+      await blobStore.getStream(hash1)
+    } catch (err) {
+      fetchError = err
+    }
+    expect(fetchError).to.exist
+    expect(fetchError.message).to.match(/not found/i)
+
+    // Check blob2 is unmodified
+    const publicContent = await blobStore.getString(hash2)
+    expect(publicContent).to.equal('Public data')
+  })
+
+  it('should redact a blob with a default message if no flag is provided', async function () {
+    const historyId = new ObjectId().toString()
+    const blobStore = new BlobStore(historyId)
+
+    const blob1 = await blobStore.putString('Confidential data')
+    const hash1 = blob1.getHash()
+
+    // Redact blob1
+    const result = await runScript([
+      '--historyId',
+      historyId,
+      '--blob',
+      hash1,
+      '--yes',
+    ])
+
+    expect(result.status).to.equal(0)
+    expect(result.stdout).to.include(`Replacing blob ${hash1}`)
+
+    // Check blob1 is redacted
+    const redactedContent = await blobStore.getString(hash1)
+    expect(redactedContent).to.match(
+      /^REDACTED \d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}\.\d{3}Z$/
+    )
+  })
+
+  it('should redact a blob with a custom message', async function () {
+    const historyId = new ObjectId().toString()
+    const blobStore = new BlobStore(historyId)
+
+    const blob1 = await blobStore.putString('Confidential data')
+    const hash1 = blob1.getHash()
+
+    // Redact blob1
+    const result = await runScript([
+      '--historyId',
+      historyId,
+      '--blob',
+      hash1,
+      '--message',
+      'MY_CUSTOM_MSG',
+      '--yes',
+    ])
+
+    expect(result.status).to.equal(0)
+    expect(result.stdout).to.include(`Replacing blob ${hash1}`)
+
+    // Check blob1 is redacted
+    const redactedContent = await blobStore.getString(hash1)
+    expect(redactedContent).to.match(
+      /^MY_CUSTOM_MSG \d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}\.\d{3}Z$/
+    )
+  })
+
+  it('should redact a blob with an empty file if --empty is used', async function () {
+    const historyId = new ObjectId().toString()
+    const blobStore = new BlobStore(historyId)
+
+    const blob1 = await blobStore.putString('Confidential data')
+    const hash1 = blob1.getHash()
+
+    // Redact blob1
+    const result = await runScript([
+      '--historyId',
+      historyId,
+      '--blob',
+      hash1,
+      '--empty',
+      '--yes',
+    ])
+
+    expect(result.status).to.equal(0)
+    expect(result.stdout).to.include(`Replacing blob ${hash1}`)
+
+    // Check blob1 is empty
+    const redactedContent = await blobStore.getString(hash1)
+    expect(redactedContent).to.equal('')
+  })
+
+  it('should redact a blob with a specific file if --file is used', async function () {
+    const historyId = new ObjectId().toString()
+    const blobStore = new BlobStore(historyId)
+
+    const blob1 = await blobStore.putString('Confidential data')
+    const hash1 = blob1.getHash()
+
+    // Create a temporary file
+    const fs = await import('node:fs/promises')
+    const os = await import('node:os')
+    const path = await import('node:path')
+
+    const tmpDir = await fs.mkdtemp(path.join(os.tmpdir(), 'redact-test-'))
+    const tmpFile = path.join(tmpDir, 'replacement.txt')
+    await fs.writeFile(tmpFile, 'Replacement file content')
+
+    try {
+      // Redact blob1
+      const result = await runScript([
+        '--historyId',
+        historyId,
+        '--blob',
+        hash1,
+        '--file',
+        tmpFile,
+        '--yes',
+      ])
+
+      expect(result.status).to.equal(0)
+      expect(result.stdout).to.include(`Replacing blob ${hash1}`)
+
+      // Check blob1 has replacement content
+      const redactedContent = await blobStore.getString(hash1)
+      expect(redactedContent).to.equal('Replacement file content')
+    } finally {
+      await fs.rm(tmpDir, { recursive: true, force: true })
+    }
+  })
+
+  it('should error when conflicting options are provided', async function () {
+    const historyId = new ObjectId().toString()
+    const blobStore = new BlobStore(historyId)
+
+    const blob1 = await blobStore.putString('Confidential data')
+    const hash1 = blob1.getHash()
+
+    // Redact blob1 with conflicting flags
+    const result = await runScript([
+      '--historyId',
+      historyId,
+      '--blob',
+      hash1,
+      '--delete',
+      '--file',
+      'dummy.txt',
+    ])
+
+    expect(result.status).to.equal(1)
+    expect(result.stderr).to.include('Error: Conflicting options provided')
+    expect(result.stderr).to.include('--delete')
+    expect(result.stderr).to.include('--file')
+  })
+})