`@fastify/swagger`

Generates an OpenAPI specification from route schemas.

Since Fastify 5 Spec ↗

Syntax

app.register(swagger, { openapi })

Parameters

Name	Type	Required	Description
`options`	`object`	No	OpenAPI document info and mode (dynamic or static).

Returns

Promise<void> — Resolves when the plugin is registered.

Examples

import Fastify from 'fastify';
import swagger from '@fastify/swagger';
import swaggerUi from '@fastify/swagger-ui';

const app = Fastify();

await app.register(swagger, {
  openapi: { info: { title: 'Cats API', version: '1.0.0' } },
});
await app.register(swaggerUi, { routePrefix: '/docs' });

app.get('/cats', {
  schema: {
    response: { 200: { type: 'array', items: { type: 'string' } } },
  },
}, async () => ['kitty']);

Notes

The spec is generated from each route's JSON Schema, so define request and response schemas. Pair with @fastify/swagger-ui to serve interactive documentation.