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This guide walks you from zero to a running HTTP server. You’ll initialize a project, write a server using Bun.serve(), and run it — all without any compilation step.
You need Bun installed before starting. See Installation if you haven’t done that yet.
1

Create a new project

Run bun init to scaffold a new project. Pass a directory name to create it in a subdirectory:
bun init my-app
Bun prompts you to choose a template. Select Blank for this guide:
✓ Select a project template: Blank

- .gitignore
- index.ts
- tsconfig.json (for editor autocomplete)
- README.md
This creates a my-app/ directory with a minimal TypeScript project. The tsconfig.json is configured for Bun and includes type definitions automatically.
2

Run the default file

Move into the project directory and run the generated index.ts:
cd my-app
bun run index.ts

Hello via Bun!
Bun executes TypeScript directly — no compilation step, no tsc, no build output.
3

Write an HTTP server

Replace the contents of index.ts with a simple HTTP server using Bun.serve():
index.ts
const server = Bun.serve({
  port: 3000,
  fetch(req) {
    return new Response("Hello from Bun!");
  },
});

console.log(`Listening on http://localhost:${server.port}`);
Run it:
bun run index.ts

Listening on http://localhost:3000
Open http://localhost:3000 in your browser. You should see Hello from Bun!.Bun.serve() accepts a fetch handler that receives a standard Request and must return a Response. These are the same Web APIs used in service workers and edge runtimes.
4

Add routing

Bun.serve() also supports a routes object for declarative routing without a framework:
index.ts
const server = Bun.serve({
  port: 3000,
  routes: {
    "/": () => new Response("Hello from Bun!"),
    "/health": () => new Response("OK"),
  },
  fetch(req) {
    // fallback for unmatched routes
    return new Response("Not found", { status: 404 });
  },
});

console.log(`Listening on http://localhost:${server.port}`);
Run it again and visit http://localhost:3000/health.
5

Add a package.json script

Open package.json and add a start script so you can run the server with a short command:
package.json
{
  "name": "my-app",
  "module": "index.ts",
  "type": "module",
  "scripts": {
    "start": "bun run index.ts"
  },
  "devDependencies": {
    "@types/bun": "latest"
  }
}
Now start the server with:
bun run start
bun run is roughly 28x faster than npm run — 6ms vs 170ms of overhead per invocation. For projects with many scripts, this adds up quickly.
You now have a working Bun HTTP server. Here are some natural next steps:

TypeScript

Learn how Bun handles TypeScript natively, including recommended tsconfig settings.

HTTP server API

Explore the full Bun.serve() API: WebSockets, TLS, streaming responses, and more.

Package manager

Install npm packages with bun add and manage dependencies faster than npm.

Test runner

Write and run Jest-compatible tests with bun test.

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