The best Tampermonkey alternative: userscript managers compared

If your userscripts stopped running in Chrome, the manager may not be the problem. Since Chrome 138, every extension that runs userscripts needs its own Allow User Scripts switch turned on, and a manager installed after that change starts with the switch off. So before you look for a Tampermonkey alternative, check that switch. If you still want a different manager, this guide compares Tampermonkey, Violentmonkey and Greasemonkey by browser, licence and sync, from each one's own pages as of 27 October 2026.

In May 2025, Chrome announced that it was replacing the single Developer mode switch with a per-extension Allow User Scripts switch, from Chrome 138. Extensions that already ran userscripts with Developer mode on were switched on once, during the move. Any extension you install after it starts with the switch off. Tampermonkey's FAQ says that from version 5.3, in a Chrome-based browser, it needs the switch (or Developer mode, in older Chrome) to run your scripts.

To turn it on, as Chrome documents it:

1. Open chrome://extensions in a new tab.
2. Find your userscript manager's card and click Details.
3. Turn on Allow User Scripts.

On a Chrome older than 138, turn on Developer mode on the same page instead. The switch belongs to each extension, so if you move to another manager, turn it on for that one too. On a work computer, your administrator can block extensions that run userscripts, and the switch may not help.

• Open source. Tampermonkey is free, and its Firefox Add-ons listing gives its licence as All Rights Reserved. Violentmonkey and Greasemonkey are both under the MIT licence, so anyone can read how they work.
• Another browser. Greasemonkey is only for Firefox. Tampermonkey and Violentmonkey both run in several browsers, but not the same set.
• Where your scripts sync. Violentmonkey syncs through a storage service you choose. Tampermonkey has a sync feature of its own.

These are the two that run in Chrome. Violentmonkey calls itself an open source userscript manager. It is MIT-licensed, and its stable Chrome build is the Manifest V3 one from the Chrome Web Store. Its page lists the Chrome Web Store, Firefox Add-ons and Microsoft Edge Add-ons, and it syncs your scripts through Dropbox, OneDrive, Google Drive or WebDAV, including between different browsers.

Tampermonkey is free, its licence is All Rights Reserved, and its site lists Chrome, Microsoft Edge, Safari, Opera Next and Firefox, so it's the one of the three that names Safari. It syncs your scripts with a feature you turn on in the extension. If you switch, install your scripts again in the new manager, then turn on Allow User Scripts for it in Chrome.

A userscript is a small piece of JavaScript that a manager runs on the pages it names, to change how they look or behave: hide a box, add a button, rearrange a list. People share userscripts on script-sharing sites and forums, and many write their own. A manager installs them, runs them on the right pages and, with sync, keeps them on each of your browsers.

One honest warning: a userscript runs on the sites you visit, with what those pages show you, including the ones you're signed in to. Violentmonkey's own page says the changes a page shows come from the scripts you install, so install only scripts you trust. Read a script before you install it, or ask someone who can.

A userscript is tied to the page it was written for, so when the site changes its layout, the script may stop working until someone fixes it. If that's the part you'd rather not do, there are two other routes. A newer kind of extension lets you describe a change to a page in plain words and has AI make it; it's a different category from a userscript manager, and the same caution about what you let run on your sites applies. Or, for a change you want to keep and share, make your own extension.

Tabless is a browser extension that builds what you ask for from the sites you allow; nothing is typed or submitted without your OK. It isn't open yet. It's a different kind of tool from the managers above: you ask in plain words for what a site is missing, such as a button, an export or one view across several of its pages, and it's designed to build that on the site you already use, inside Tabless.

It's designed to read through the session your browser already has, so there are no API keys or passwords to hand over, and to ask before it reads each site. You sign in to Tabless with a Wix account.

Violentmonkey's page says it contains no ads and doesn't change pages by itself: what changes is up to the userscripts you install, so install only ones you trust. It is open source under the MIT licence, so its workings can be read by anyone. A script you install is a separate matter from the manager, and is only as safe as whoever wrote it.

Yes. Greasemonkey is a Firefox extension, including on Firefox for Android, and Violentmonkey and Tampermonkey are both on Firefox Add-ons. The Allow User Scripts switch described above is a Chrome setting.

Not yet. Tabless isn't open, and adding what a site is missing, such as a button or an export, is among the jobs we're building it for. Join the waitlist, and we'll let you know when you can try Tabless.