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Bun Playground

Overview

The playground runs a Bun project entirely in your browser:

  • Bun’s own code, compiled to wasm64. The transpiler, bundler and semver come from Bun’s Rust crates that don’t depend on JavaScriptCore, built for 64-bit WebAssembly (Memory64).
  • JS shims for the runtime. Bun.*, bun:* and node:* APIs are implemented in JavaScript on top of the browser’s engine.
  • A virtual file system. Your project lives in memory and is saved to the browser’s storage.
  • A service worker serves your modules and the preview of Bun.serve and node:http servers.

Because the runtime is a set of shims, not every Bun or Node API is there yet. Check Compatibility before porting a project, and the Features tour for what the playground can do.