Why it's a strong pick

Tampermonkey is a userscript manager that is free, according to the developer's download list. The Chrome Web Store listing shows version 5.5.1, updated 4 October 2026. It manages, edits, syncs and updates your scripts in one place. The catch: on current Chrome, scripts do not run until you switch on one setting.

What it does

Tampermonkey runs userscripts. A userscript is a small piece of code that changes a website for you. It can change a page layout, add or remove a feature, or automate an action. The listing says you can "change the web at will with userscripts". Tampermonkey installs the scripts, keeps them updated and lets you turn each one on or off.

Key features

Script management. Turn scripts on or off in two clicks and edit them in a built-in editor.
Syntax checking. The editor uses ESLint to flag code errors.
Sync. Sync through Chrome Sync or cloud services: Google Drive, Dropbox, OneDrive, Yandex.Disk and WebDAV.
Backup and restore. Back up to a zip file or to the cloud.
Automatic updates. Scripts can update themselves.
Site blacklist. Stop scripts from running on sites you choose.

Who it's for

Tampermonkey suits people who want to change websites with scripts they find or write, and script authors who want an editor and sync in one tool. The official site links to userscript.zone for finding scripts. It is not for anyone who only wants a simple blocker or theme: a normal extension is easier.

How do I get Tampermonkey scripts to run in Chrome?

Turn on the "Allow User Scripts" toggle for Tampermonkey in Chrome's extension settings. The developer's FAQ says Tampermonkey 5.3 and later needs this toggle on Chrome 138 or newer. On older Chrome, turn on Developer Mode instead. Until you do, installed scripts will not run.

Does Tampermonkey work with Manifest V3?

Yes. The official changelog has an "MV3" section starting with version 5.3.0, dated 15 September 2024. Manifest V3 is Chrome's current extension format. The developer's FAQ also has an entry on how to keep running a Manifest V2 version; we have not read it, so we do not describe it here.

What does Tampermonkey do with my data?

On the Chrome Web Store privacy tab, the developer discloses collecting location and user activity. It describes anonymous usage info, such as version, language and browser type, and automatic error reports. You can turn this off with the "Anonymous statistics" setting. Incognito sends no usage info. Blacklist and update checks include your IP address.

FAQ

Is Tampermonkey free? Yes. The developer's download list says "Free". The Chrome Web Store listing shows no price.

Is Tampermonkey open source? The developer does not state a source licence on the pages we read, so we do not claim it.

Do I need an account? The developer does not say that an account is required. Cloud sync is optional.

Good to know

Turn on "Allow User Scripts" first, or nothing will run. The stable and beta builds need Chrome 120 or newer, per the official site. Chrome shows the exact permission list when you install, so read it. Add scripts only from sources you trust, because a script can read and change the pages it runs on. If you do not want usage data sent, switch off "Anonymous statistics" in the settings.

Other userscript managers to compare

Tampermonkey is one of 3 picks in our userscript managers guide:

Violentmonkey: an open-source userscript manager. MIT licence.
ScriptCat: Tampermonkey-compatible, with background and scheduled scripts. Open source (GPL-3.0).

Related: developer tools.

Official sources

Official site and changelog
FAQ (Allow User Scripts, Q209)
Chrome Web Store listing