Bun quickstart: 5-minute local dev environment
The shortest path to getting Bun running — a minimal starting point for first-time users.
Quick answer
How does Bun differ from the Node API?
Bun fs and a few APIs differ from Node. Pin the Bun version in CI to avoid local-works-but-CI-breaks surprises.
Machine-readable page data: /data/bun-quickstart.json
In-depth analysis
Bun unifies runtime, package manager, and bundler into one toolchain, beating Node on startup and install speed. It pairs especially well with AI coding workflows. The fastest path to a win is one command to scaffold, start dev, edit a line, and see hot reload.
// Local server + script runner with Bun (zero extra deps)
Bun.serve({ port: 3000, fetch: () => new Response('hi') });
// Install: bun install Run: bun run dev Build: bun build ./src/index.tsBun Quickstart · Key takeaways
- Node ≥ 20.19 and pnpm ready
- Official scaffold initialized
- Dev hot reload works
- First local page reached
FAQ & pitfalls
Why does my existing project break when I run it on Bun?
Native modules may be missing or APIs differ. Bootstrap new projects with bun first, then migrate legacy projects gradually and fill in types.
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What readers are asking
Questions that keep coming back in reader feedback, already answered.
- 01
Why does the same project error out when I run it with Bun?
Native modules are missing, or some Node APIs behave differently under Bun. Pin the Bun version in CI; migrate older projects gradually and initialise new ones with Bun directly.
See the full guide → - 02
Why is my Astro component's interactivity not working?
Components ship as zero-JS HTML by default, so an interactive one needs a client:* directive (client:load, client:visible, …). Without it the script is never bundled into the page.
See the full guide → - 03
Why is my custom Tailwind v4 brand colour not applied?
Colours must be declared in @theme (for example --color-brand). A missing @tailwindcss/vite plugin, or a leftover v3 config, makes bg-brand silently render nothing.
See the full guide →