`app.post()`

Registers a route handling HTTP POST requests, typically with a body schema.

Since Fastify 5 Spec ↗

Syntax

app.post(url, options?, handler)

Parameters

Name	Type	Required	Description
`url`	`string`	No	The route path.
`options`	`RouteShorthandOptions`	No	Optional schema (body/response), hooks, and config.
`handler`	`Function`	No	Async handler receiving (request, reply).

Returns

FastifyInstance — The instance, for chaining.

Examples

import Fastify from 'fastify';

const app = Fastify();

const bodySchema = {
  type: 'object',
  required: ['name'],
  properties: { name: { type: 'string', minLength: 1 } },
} as const;

app.post<{ Body: { name: string } }>(
  '/cats',
  { schema: { body: bodySchema } },
  async (req, reply) => {
    reply.code(201);
    return { created: req.body.name };
  },
);

Notes

Define a `body` JSON Schema so invalid payloads are rejected with a 400 before the handler runs. Set the status with reply.code(201) for created resources.