Code Runner
Write and run JavaScript or Python code instantly in your browser. Multi-file support with zip import.
100% In-Browser Processing. Your files never leave your device.
index.js
Loading editor...
Terminal
Press Ctrl+Enter to run
Runs in a sandboxed iframe
index.jsLn 13
About this tool
Code Runner is a free, browser-based code editor and execution environment that supports JavaScript and Python. It features a full Monaco editor (the same editor that powers VS Code) with syntax highlighting, code folding, and bracket matching. JavaScript runs in a sandboxed iframe for security, while Python runs via Pyodide — a full CPython 3.12 runtime compiled to WebAssembly. You can work with multiple files, import zip archives, and see output in a real-time terminal. Everything runs locally in your browser — no code is sent to any server.