Quick Start

Minimal server:

import Fastify from 'fastify'
const app = Fastify({ logger: true })
app.get('/health', async () => ({ status: 'ok' }))
await app.listen({ port: 3000, host: '0.0.0.0' })

Plugin with shared decorators via fastify-plugin (escapes encapsulation):

import fp from 'fastify-plugin'

export default fp(async function dbPlugin(app, options) {
  const db = await createConnection(options.connectionString)
  app.decorate('db', db)
  app.addHook('onClose', async () => db.close())
}, { name: 'db-plugin' })

Route with TypeBox schema validation (preferred over raw JSON Schema):

import { Type, type Static } from '@sinclair/typebox'

const Body = Type.Object({ name: Type.String({ minLength: 1 }) })
type BodyType = Static<typeof Body>

app.post<{ Body: BodyType }>('/users', {
  schema: { body: Body, response: { 201: Type.Object({ id: Type.String() }) } }
}, async (request, reply) => {
  reply.code(201)
  return { id: await createUser(request.body) }
})

Recommended Reading Order for Common Scenarios

• New to Fastify? Start with plugins.md → routes.md → schemas.md
• Adding authentication: plugins.md → hooks.md → authentication.md
• Improving performance: schemas.md → serialization.md → performance.md
• Setting up testing: routes.md → testing.md
• Going to production: logging.md → configuration.md → deployment.md

How to use

Read individual rule files for detailed explanations and code examples:

• rules/plugins.md - Plugin development and encapsulation
• rules/routes.md - Route organization and handlers
• rules/schemas.md - JSON Schema validation
• rules/error-handling.md - Error handling patterns
• rules/hooks.md - Hooks and request lifecycle
• rules/authentication.md - Authentication and authorization
• rules/testing.md - Testing with inject()
• rules/performance.md - Performance optimization
• rules/logging.md - Logging with Pino
• rules/typescript.md - TypeScript integration
• rules/decorators.md - Decorators and extensions
• rules/content-type.md - Content type parsing
• rules/serialization.md - Response serialization
• rules/cors-security.md - CORS and security headers
• rules/websockets.md - WebSocket support
• rules/database.md - Database integration patterns
• rules/configuration.md - Application configuration
• rules/deployment.md - Production deployment
• rules/http-proxy.md - HTTP proxying and reply.from()