Fastify

This guide covers adding debugger to a Fastify project. The setup takes one line.

Fastify official docs

Install

npm install -D @ephem-sh/debugger

Set up

Register the debugger plugin with your Fastify instance:

import Fastify from 'fastify'
import { debuggerPlugin } from '@ephem-sh/debugger/fastify'

const fastify = Fastify({ logger: true })
await fastify.register(debuggerPlugin, { port: 3000 })

The plugin registers browser routes, adds onRequest/onResponse hooks for HTTP timing, and starts the IPC bridge.

Browser support

Add script tags before </body> in your HTML responses:

<script>window.__DEBUGGER_INGEST_URL__="/_/d";</script>
<script src="/_/d.js" defer></script>

Verify

node server.mjs

npx dbg status

pnpm dlx dbg status

bun x dbg status

yarn dlx dbg status

npx dbg browser console

pnpm dlx dbg browser console

bun x dbg browser console

yarn dlx dbg browser console

Full example

See the complete working example at examples/node/fastify.