SourceMonkey

A userscript manager that treats userscripts like source code, built and managed with real developer tools, including coding agents

SourceMonkey is a userscript manager built for developing userscripts with real coding tools, and especially with coding agents like Claude Code. Userscripts are small JavaScript patches that change how specific web pages look or work. They're like lightweight extensions that are easy to write, update and share. A userscript manager stores your scripts and runs them on the pages they target. HOW SOURCEMONKEY IS DIFFERENT Most userscript managers are script editors: you write scripts in a text box inside the browser. SourceMonkey treats userscripts as source code instead. • Your scripts live in a folder on your own disk, or in a GitHub repo. • You edit them with your own editor or IDE, keep them in version control, or have a coding agent write them. • SourceMonkey picks up each change right away. Switch back to the browser and reload the page. • The script you develop is the same file you publish. @require files can load from your local folder while you work, with no edits. You can also install scripts from the web, from sites like Greasy Fork or a GitHub repo. SourceMonkey updates them when the source publishes new versions. BUILT FOR AGENTIC DEVELOPMENT Ask your coding agent "Build me a script that does X on site Y." The agent writes the script and tries it on the real page, using SourceMonkey's developer tools. If it doesn't work, the agent debugs it and tries again. When it's done, reload the page in your own browser to see the result. To change anything, just ask. DEVELOPER TOOLS SourceMonkey's developer tools are on npm (npx sm-dev): • sm-dev, a command-line tool to run a script in a real browser, inspect and drive the page, and read the script's logs and stored values. • A Playwright test fixture for writing automated tests of your userscripts. • Skills that teach coding agents how to use these tools to write userscripts. FEATURES • Install any .user.js link, with a pre-install preview and validation. • Load script "collections": load all the userscripts in a local folder or a GitHub repo, and keep them in sync. • Supports all common GM* APIs and script headers, compatible with Tampermonkey and Violentmonkey scripts. • Import and export scripts across other managers. PRIVACY SourceMonkey collects no data. It has no analytics, tracking or account, and your scripts and settings stay in your browser. Privacy policy: https://github.com/jshute96/SourceMonkey/blob/main/PRIVACY.md OPEN SOURCE For source code and documentation: https://github.com/jshute96/SourceMonkey