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reactnative.run

reactnative.run

Mar 27, 2026 Developer Tools

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reactnative.run

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We built browser-metro, a Metro-like bundler that runs entirely in a Web Worker. It supports full HMR with React Refresh, Expo Router with file-based routing, and on-demand npm package resolution via an ESM server. API routes run in-browser through fetch interception — no server or service worker needed. Unlike Expo Snack (server-side bundling) or CodeSandbox, everything here happens client-side. Currently web-preview only; native device preview is on the roadmap.Open source (MIT): https://github.com/RapidNative/reactnative-run

Comments (3)

Matilda Krajcik Matilda Krajcik 3 months ago

bet this chokes on any real project

Uriah Renner Uriah Renner 3 months ago

whats the cold start latency like with on-demand npm resolution

Jaylan O'Hara Jaylan O'Hara 3 months ago

Full HMR in a web worker is beautifully unhinged engineering.