TamperJS — Inject Javascript Easily

Inject, tweak, and customize JavaScript on any website with a powerful Monaco-powered editor.

TamperJS is a lightweight and efficient browser extension designed for developers who need a quick and seamless way to inject custom JavaScript into any website. Built with the Monaco Editor—the same technology behind VS Code—it provides a clean and intuitive environment for writing, testing, and executing scripts effortlessly. Whether you're a developer optimizing workflows, a researcher testing scripts, or a power user customizing web pages, TamperJS provides an easy-to-use interface with domain-based script management, instant execution, and a seamless dark mode for a comfortable coding experience. Our goal is to keep things simple yet effective, helping you customize the web in a way that suits your needs.