Userscripts are mainly javascript extensions for web browsers. Userscripts automate or customize actions, and they can change the layout or even "mash up" different websites.

Userscripts primarily refers to JavaScript extensions for web browsers. Userscripts can automate or customize actions, and/or they can change the layout or even "mash up" different websites.

Additionally, on most browsers, userscripts have access to an extended API that allows actions that are not permitted for ordinary JavaScript code running in the page scope.

Userscripts are available in most browsers:

  • Opera: Natively supported.
  • Firefox: Support via the Greasemonkey and Scriptish add-on.
  • Google Chrome: Natively supported (Greasemonkey script are supported by the Tampermonkey extension).
  • Internet Explorer: Support via Trixie extension.
  • Safari 4-: Supported after installing SIMBL and GreaseKit.
  • Safari 5+: Supported via NinjaKit (Japanese site, download link in English).

Scripts meant for Greasemonkey or Tampermonkey should be tagged , instead.
If the userscript is meant to be cross-browser compatible, use both and .


  1. A detailed guide for enabling User scripts in all major browsers.
  2. Google Chrome, Userscripts, design document
  3. Opera, User JavaScript documentation
  4. Chrome-compatible userscripts at userscripts.org
  5. Opera-compatible userscripts at userscripts.org
  6. Greasemonkey wiki
  7. Scriptish wiki
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