When to use
Use this skill when you need to:
- Develop backend applications using Fastify
- Implement Fastify plugins and route handlers
- Get guidance on Fastify architecture and patterns
- Use TypeScript with Fastify (strip types)
- Implement testing with Fastify's inject method
- Configure validation, serialization, and error handling
Quick Start
A minimal, runnable Fastify server to get started immediately:
import Fastify from 'fastify'
const app = Fastify({ logger: true })
app.get('/health', async (request, reply) => {
return { status: 'ok' }
})
const start = async () => {
await app.listen({ port: 3000, host: '0.0.0.0' })
}
start()
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()
Core Principles
- Encapsulation: Fastify's plugin system provides automatic encapsulation
- Schema-first: Define schemas for validation and serialization
- Performance: Fastify is optimized for speed; use its features correctly
- Async/await: All handlers and hooks support async functions
- Minimal dependencies: Prefer Fastify's built-in features and official plugins
---
name: fastify-best-practices
description: Guides development of Fastify Node.js backend servers and REST APIs using TypeScript or JavaScript, covering routes, plugins, validation, error handling, authentication, testing, performance, logging, deployment, and more.
---
## When to use
Use this skill when you need to:
- Develop backend applications using Fastify
- Implement Fastify plugins and route handlers
- Get guidance on Fastify architecture and patterns
- Use TypeScript with Fastify (strip types)
- Implement testing with Fastify's inject method
- Configure validation, serialization, and error handling
## Quick Start
A minimal, runnable Fastify server to get started immediately:
```ts
import Fastify from 'fastify'
const app = Fastify({ logger: true })
app.get('/health', async (request, reply) => {
return { status: 'ok' }
})
const start = async () => {
await app.listen({ port: 3000, host: '0.0.0.0' })
}
start()
```
## 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](rules/plugins.md) - Plugin development and encapsulation
- [rules/routes.md](rules/routes.md) - Route organization and handlers
- [rules/schemas.md](rules/schemas.md) - JSON Schema validation
- [rules/error-handling.md](rules/error-handling.md) - Error handling patterns
- [rules/hooks.md](rules/hooks.md) - Hooks and request lifecycle
- [rules/authentication.md](rules/authentication.md) - Authentication and authorization
- [rules/testing.md](rules/testing.md) - Testing with inject()
- [rules/performance.md](rules/performance.md) - Performance optimization
- [rules/logging.md](rules/logging.md) - Logging with Pino
- [rules/typescript.md](rules/typescript.md) - TypeScript integration
- [rules/decorators.md](rules/decorators.md) - Decorators and extensions
- [rules/content-type.md](rules/content-type.md) - Content type parsing
- [rules/serialization.md](rules/serialization.md) - Response serialization
- [rules/cors-security.md](rules/cors-security.md) - CORS and security headers
- [rules/websockets.md](rules/websockets.md) - WebSocket support
- [rules/database.md](rules/database.md) - Database integration patterns
- [rules/configuration.md](rules/configuration.md) - Application configuration
- [rules/deployment.md](rules/deployment.md) - Production deployment
- [rules/http-proxy.md](rules/http-proxy.md) - HTTP proxying and reply.from()
## Core Principles
- **Encapsulation**: Fastify's plugin system provides automatic encapsulation
- **Schema-first**: Define schemas for validation and serialization
- **Performance**: Fastify is optimized for speed; use its features correctly
- **Async/await**: All handlers and hooks support async functions
- **Minimal dependencies**: Prefer Fastify's built-in features and official plugins
