# Streaming HTTP Server with Async Iterators (/docs/guides/http/stream-iterator)

<!-- agent-signals: reading_time_min: 1 · est_tokens: 281 · updated: 2026-07-28 -->
Related: [Common HTTP server usage](/docs/guides/http/server.md), [Write a simple HTTP server](/docs/guides/http/simple.md), [Send an HTTP request using fetch](/docs/guides/http/fetch.md), [Hot reload an HTTP server](/docs/guides/http/hot.md), [Start a cluster of HTTP servers](/docs/guides/http/cluster.md), [Configure TLS on an HTTP server](/docs/guides/http/tls.md)

In Bun, a [`Response`](https://developer.mozilla.org/en-US/docs/Web/API/Response) accepts an async generator function as its body, so you can stream data to the client as it becomes available rather than waiting for the entire response to be ready.

```ts stream-iterator.ts icon="/icons/typescript.svg"
Bun.serve({
  port: 3000,
  fetch(req) {
    return new Response(
      // An async generator function
      async function* () {
        yield "Hello, ";
        await Bun.sleep(100);
        yield "world!";

        // you can also yield a TypedArray or Buffer
        yield new Uint8Array(["\n".charCodeAt(0)]);
      },
      { headers: { "Content-Type": "text/plain" } },
    );
  },
});
```

***

You can pass any async iterable directly to `Response`:

```ts stream-iterator.ts icon="/icons/typescript.svg"
Bun.serve({
  port: 3000,
  fetch(req) {
    return new Response(
      {
        [Symbol.asyncIterator]: async function* () {
          yield "Hello, ";
          await Bun.sleep(100);
          yield "world!";
        },
      },
      { headers: { "Content-Type": "text/plain" } },
    );
  },
});
```