Bun hands-on tutorial: from zero to your first runnable project
Step-by-step walkthrough of Bun with copy-paste commands, directory layout, and a first runnable artifact.
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-tutorial.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. Going from zero to a first runnable project is about locking in the smallest end-to-end loop before you scale.
// 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 Hands-on Tutorial · Key takeaways
- Project initialized with the official scaffold
- Dependencies pinned to a single pnpm lockfile
- Local dev server starts and first paint is reachable
- First runnable commit pushed
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.
Explore the hub
See all 5 guides in BunSame category as this article, sorted across the codebase.
Bun architecture: layered patterns for high-concurrency edge apps
The edge-delivery view of Bun's layering and data flow.
Bun best practices: engineering conventions for production
Field-tested Bun practices from production, avoiding the common anti-patterns.
Bun deployment guide: zero-ops edge publishing with Cloudflare Pages
Git-driven Bun deployment in practice: commit to build, atomic publish to every edge node.
Bun performance tuning: push first paint and edge response to the limit
Around Bun's real bottlenecks, an actionable LCP / INP / CLS checklist.
Share & save
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 →