`onRequest hook`

Runs first in the request lifecycle, before body parsing and validation.

Since Fastify 5 Spec ↗

Syntax

app.addHook('onRequest', async (request, reply) => {})

Parameters

Name	Type	Required	Description
`request`	`FastifyRequest`	No	The incoming request (body not yet parsed).
`reply`	`FastifyReply`	No	The reply object.

Returns

void | Promise<void> — Throw or send to short-circuit.

Examples

import Fastify from 'fastify';

const app = Fastify();

app.addHook('onRequest', async (req, reply) => {
  if (!req.headers.authorization) {
    reply.code(401).send({ error: 'Unauthorized' });
  }
});

Notes

request.body is undefined here because parsing has not run yet. Ideal for authentication, rate limiting, and request logging. Sending a reply or throwing stops the pipeline.