| 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 | | Always working |
| Firebug | Firefox extension for developers | Allows arbitrary real time changes to a page's DOM | | 2017 |
| Greasemonkey | Browser extension | Alters the output of web content immediately after being displayed | Firefox, Chromium browser and Opera. | 2021 |
| Tampermonkey | Browser extension | Userscripts manager that provides features like a clear overview over the running scripts, a built-in editor, ZIP-based import and export, automatic update checks, and browser- and cloud storage-based synchronization | Firefox, Chromium browser and Opera. | 2025 |
| iMacros | Firefox, Chromium browser, and Internet Explorer extension | Allows the user to record and replay "Internet Macros" for web automation, web scraping, or web testing. | | 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 | | 2022 |
| Violentmonkey | Browser extension | open source alternative to Greasemonkey | | 2024 |
| Userscripts | Browser extension | Supports writing Userscripts and Userstyles | Safari | 2024 |