fastify

name	fastify
description	Production Fastify (TypeScript) patterns: schema validation, plugins, typed routes, error handling, security hardening, logging, testing with inject, and graceful shutdown
user-invocable	false
disable-model-invocation	true
version	1.0.0
category	toolchain
author	Claude MPM Team
license	MIT
progressive_disclosure	{"entry_point":{"summary":"Build fast, type-safe Node APIs with Fastify using schema-first validation, plugin encapsulation, and production middleware patterns","when_to_use":"When building TypeScript backends needing high performance, schema-based validation, clean plugin composition, and strong testability","quick_start":"1. Create Fastify instance 2. Add Type Provider (Zod/TypeBox) 3. Register plugins (CORS/Helmet) 4. Add error handler + logging 5. Test with inject()"},"token_estimate":{"entry":130,"full":5200}}
context_limit	900
tags	["typescript","fastify","nodejs","api","validation","json-schema","security","testing"]
requires_tools	[]

Fastify (TypeScript) - Production Backend Framework

Overview

Fastify is a high-performance Node.js web framework built around JSON schema validation, encapsulated plugins, and great developer ergonomics. In TypeScript, pair Fastify with a type provider (Zod or TypeBox) to keep runtime validation and static types aligned.

Quick Start

Minimal server

✅ Correct: basic server with typed response

import Fastify from "fastify";

const app = Fastify({ logger: true });

app.get("/health", async () => ({ status: "ok" as const }));

await app.listen({ host: "0.0.0.0", port: 3000 });

❌ Wrong: start server without awaiting listen

app.listen({ port: 3000 });
console.log("started"); // races startup and hides bind failures

Schema Validation + Type Providers

Fastify validates requests/responses via JSON schema. Use a type provider to avoid duplicating types.

Zod provider (recommended for full-stack TypeScript)

✅ Correct: Zod schema drives validation + types

import Fastify from "fastify";
import { z } from "zod";
 {  }  ;

 app = ({ :  }).<>();

  = z.({ : z.().() });

app.(
  ,
  { : { :  } },
   (req) => {
     { : req.. };
  },
);

 app.({ :  });