Commonly opened with
  • Tampermonkey
  • Greasemonkey
  • Violentmonkey
Supported platforms
  • Windows
  • macOS
  • Linux
  • Web / Cross-platform
Editable?
Yes, with common software
Viewable without special tools?
Usually, yes
Inherent format risk
Use some caution
Safety guidance (not a guarantee)

Userscripts run automatically on the pages you visit and can read or modify page content. Only install userscripts from authors and sources you trust.

Check another filename

File extension lookup

No upload, no sign-up — everything is analyzed locally in your browser.

Frequently asked questions

What is a .user.js file?

A JavaScript file meant to be run by a userscript manager (like Tampermonkey or Greasemonkey) to modify how specific web pages look or behave.

Can I edit a .user.js file?

Yes — .user.js files are commonly editable with software such as Tampermonkey.

Does having a .user.js extension mean the file is safe?

No single extension can guarantee that. Userscripts run automatically on the pages you visit and can read or modify page content. Only install userscripts from authors and sources you trust. Always consider where the file came from, not just its name.

Privacy: The lookup above runs entirely in your browser. Nothing you type is uploaded, logged, or sent anywhere.

← Back to the file extension lookup tool