About Online JS Compiler

A simpler place to write and run JavaScript.

Online JS Compiler is a browser-based development workspace for experimenting with JavaScript, understanding runtime behavior, and creating focused test cases without setting up a local project.

Built for learning and shipping

Use a familiar editor, run code, inspect console output, and iterate quickly. The experience is designed for developers learning a concept, validating a small idea, or preparing a reproducible example.

Browser-first by design

The application runs in the browser. Code execution is isolated from the main interface, while local workspace state stays on your device unless you intentionally use an external service.

What you can do here

Run JavaScript online. Execute snippets and inspect console output in a responsive workspace.
Generate Smart or AI Tests. Analyze functions locally with Smart Tests, or use your own provider key for AI-generated cases, assumptions, and explanations.
Learn by experimenting. Try examples, isolate bugs, and compare results without a full project setup.
Keep control of your code. Review what runs, where it runs, and which external provider receives a request.

Have an idea or a problem?

We want the playground to stay fast, understandable, and useful for everyday JavaScript work.