# Bun Hot reload an HTTP server

> Hot reload an HTTP server

- Skill: `jarle/bun-hot-reload-an-http-server` (Agent Skill)
- Install (CLI): `npx skillmds@latest add jarle/bun-hot-reload-an-http-server`
- Raw SKILL.md: https://api.skillmd.com/api/skills/jarle/bun-hot-reload-an-http-server/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: jarle (https://skillmd.com/u/jarle)
- Updated: 2026-09-21
- Page: https://skillmd.com/skills/jarle/bun-hot-reload-an-http-server

---


# Hot reload an HTTP server

Bun supports the [`--hot`](/runtime/watch-mode#hot-mode) flag to run a file with hot reloading enabled. When any module or file changes, Bun re-runs the file.

```sh terminal icon="terminal" theme={"theme":{"light":"github-light","dark":"dracula"}}
bun --hot run index.ts
```

***

Bun detects when you are running an HTTP server with `Bun.serve()`. It reloads your fetch handler when source files change, *without* restarting the `bun` process. This makes hot reloads nearly instantaneous.

<Note>
  Note that this doesn't reload the page on your browser.
</Note>

```ts index.ts icon="https://mintcdn.com/bun-1dd33a4e/nIz6GtMH5K-dfXeV/icons/typescript.svg?fit=max&auto=format&n=nIz6GtMH5K-dfXeV&q=85&s=5d73d76daf7eb7b158469d8c30d349b0" theme={"theme":{"light":"github-light","dark":"dracula"}}
Bun.serve({
  port: 3000,
  fetch(req) {
    return new Response("Hello world");
  },
});
```