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Fastify From Zero

Learn the fast, schema-first Node.js framework: routing with JSON-schema validation and serialization, the encapsulated plugin system, the request/reply lifecycle and hooks, building a REST API, error handling, and testing and production. A modern, performance-focused alternative to Express that bakes in validation and structure.

  1. What Fastify Is & Your First Server Fastify is the fast, schema-first Node.js framework — an Express alternative with validation built in. Install it, write a tiny async server, run it, and meet the two ideas that define it.
  2. Routing & Schemas Routing in Fastify by method, params, query, and body — and attaching a JSON Schema to a route so Fastify validates input and fast-serializes output for you, no validation code required.
  3. The Plugin System How Fastify organizes apps as a tree of encapsulated plugins: writing a plugin, registering it with a prefix, decorating the instance, and using fastify-plugin to share across the whole app.
  4. Hooks & the Lifecycle Every request flows through a named request/reply lifecycle. Hooks let you run code at each stage — onRequest, preHandler, onSend — and they respect plugin encapsulation, so you can guard one route group cleanly.
  5. Building a REST API Assemble routing, schemas, plugins, and hooks into a full books CRUD API: five schema-backed routes in one encapsulated plugin over an in-memory collection, with tiny handlers because validation lives in the schema.
  6. Error Handling How Fastify makes most error handling automatic — schema-validation 400s and auto-caught async throws — and how one setErrorHandler, typed errors, and setNotFoundHandler shape the rest into consistent responses.
  7. Testing & Production Test the books API in process with Fastify's built-in app.inject(), structure the app as a buildApp() function, then harden for production with pino logging, graceful shutdown, env config, and official plugins.
  8. Where to Go Next What you can build now, how Fastify compares to Express, NestJS, and bare node:http, the @fastify/* plugin ecosystem, TypeScript type providers, and one concrete thing to go build.