| Name |
Form |
Features |
Compatibility |
Last Updated |
| bookmarklets |
JavaScript |
Can execute arbitrary JavaScript on any page, but requires a user to click them, rather than running automatically |
Firefox, Chromium browser, and Safari |
Builtin |
| Firebug |
Firefox extension for developers |
Allows arbitrary real time changes to a page's DOM |
Firefox |
2017 |
| Greasemonkey |
Browser extension |
Open source userscript manager. Alters the output of web content immediately after being displayed. |
Firefox, Firefox for Android |
2024 |
| ScriptCat[1][2] |
Browser extension |
Open source userscript manager compatible with Greasemonkey/Tampermonkey-style scripts; supports background scripts, scheduled scripts, and cloud sync |
Firefox, Firefox for Android, and Chrome |
2026 |
| Tampermonkey |
Browser extension |
Closed source userscript manager that provides features including an overview over the running scripts, a built-in editor, ZIP-based import and export, automatic update checks, and browser- and cloud storage-based synchronization |
Chrome, Edge, Firefox, Opera, Safari |
2025 |
| Tweeks[3][4] |
Browser extension |
Creates site-specific modifications and functions as a userscript manager compatible with Greasemonkey/Tampermonkey-style scripts; extends the scripting API with capabilities including email sending and on-page Generative AI inference |
Firefox and Chromium browser |
2026 |
| iMacros |
Browser extension |
Allows the user to record and replay "Internet Macros" for web automation, web scraping, or web testing. |
Firefox, Chromium browser, and Internet Explorer |
2018 |
| Proxomitron |
Proxy-level language |
Available since late 1990s, predates JavaScript active browsing and provides a similar function for all browsers using a regular expression-like matching language |
|
2003 |
| Stylish |
Firefox extension using Cascading Style Sheets |
Client-side manipulation of webpage content |
Firefox |
2022 |
| Violentmonkey[5] |
Browser extension |
Open source userscript manager |
Edge, Firefox, Firefox for Android, Opera |
2026 |
| Userscripts[6] |
Browser extension |
Supports writing Userscripts (JavaScript) and Userstyles (CSS) |
Safari |
2024 |
