About

Origin story

reactnative.run started as an experiment to see if a Metro-like bundler could run entirely in the browser.

The previous version used ES Modules to run React Native code directly in the browser - each module was loaded as a native ESM import. While this worked, it had limitations with CommonJS packages and didn't match how Metro actually works.

The current version takes a different approach: it's a CommonJS bundler that mirrors Metro's architecture but runs entirely client-side. It walks the dependency graph, transforms files with Sucrase, rewrites require() calls, and emits a single self-executing bundle - just like Metro does, but in a Web Worker instead of a Node.js process.

You can read more about the technical journey in this Expo blog post: How to build a dev server in the browser.

Author

Sanket Sahu is the primary author of reactnative.run and browser-metro.

RapidNative

reactnative.run is built and maintained by RapidNative.

Open source

The entire project is open source under the MIT license:

  • browser-metro - the core bundler library
  • reactnative-esm - the npm package server
  • reactnative.run - the playground and website

Source code: github.com/RapidNative/reactnative-run

Disclaimer

This project is not affiliated with, endorsed by, or associated with Meta, Facebook, the React Native team, or the React Foundation. React Native is a trademark of Meta Platforms, Inc. The domain name "reactnative.run" is simply a descriptive name for this open-source tool.

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