ScriptCat is a browser extension that executes userscripts and manages their execution across web pages.
ScriptCat addresses the need to customize and automate web browsing by running userscripts in the browser. It builds on Tampermonkey's design philosophy while adding its own innovations. The tool maintains full compatibility with existing Tampermonkey scripts, allowing users to migrate without friction. Beyond traditional page-level script execution, ScriptCat introduces a background script framework that keeps scripts running continuously independent of page state, enabling more persistent automation. It also supports scheduled script execution for time-based tasks and provides an expanded API surface compared to Tampermonkey. Scripts run in sandboxed environments to prevent malicious code from affecting other scripts, and the permission system requires explicit requests with additional confirmation for sensitive operations.
ScriptCat suits developers and power users who want to extend browser functionality through scripting. It works well for ad removal, task automation, page customization, and workflows requiring persistent background execution or scheduled triggers. The built-in code editor with intelligent completion and syntax checking streamlines script development. Users with existing Tampermonkey scripts can adopt it without rewriting code. The tool supports cloud synchronization of scripts across devices and allows creation of script collections for team collaboration.
The project maintains active development with passing build checks and code coverage tracking. The tool is available across multiple browsers including Chrome, Edge, and Firefox through their respective extension stores. Documentation is comprehensive and accessible, with community support available through Discord.
