Tampermonkey: Run Userscripts in Chrome Safely

Userscripts are small JavaScript programs that change websites: they can rearrange a page, add a missing button, hide clutter or automate a repetitive click. Tampermonkey is the manager that installs and runs them in Chrome.

What Tampermonkey offers

• Script editor and manager: write, edit and organize your userscripts.
• Quick toggles: switch any script on or off in a couple of clicks.
• Sync: synchronize scripts through Chrome Sync or cloud storage such as Google Drive, Dropbox, OneDrive, Yandex.Disk and WebDAV.
• Backups: export and restore settings and scripts as zip files.
• Automatic updates for installed scripts.

The extra step in current Chrome

Chrome asks for a second, explicit permission before an extension can run userscripts. According to Tampermonkey’s FAQ, users of version 5.3 or later in Chrome must enable either the Allow User Scripts toggle (available in Chrome 138 and later) or Developer Mode. To do it, right-click the Tampermonkey icon, choose Manage Extension, and switch on Allow User Scripts.

Installing it

1. The Download button opens the official Tampermonkey listing on the Chrome Web Store.
2. Click Add to Chrome, then enable Allow User Scripts as described above.
3. Install scripts from sources you trust, or create your own from the dashboard.

Be careful with scripts

Tampermonkey itself is widely used, but every userscript you add runs code on the pages it targets, and a malicious one could read what you see or type there. Read a script before installing it and avoid unknown sources. Tampermonkey says it collects anonymous usage information to improve the extension, and the store listing discloses that it handles location and user activity data. The extension is free to use. If all you want is a dark theme on every site, Dark Reader does that without any scripts.