Why Fastify in 2026
The Node.js web framework landscape is crowded, but Fastify has carved out a distinct position: raw performance without sacrificing developer experience. In benchmark circles it routinely outperforms Express by 2-3x on request throughput while maintaining a plugin ecosystem that covers most of what you need out of the box.
TypeScript support is first-class in 2026. The framework ships with type definitions, and the plugin ecosystem makes it straightforward to share types between your route definitions, validation schemas, and API documentation.
Project Setup
Start by scaffolding with TypeScript, Fastify, and the essential plugins. Core dependencies: fastify, @fastify/cors, @fastify/rate-limit, @fastify/swagger for OpenAPI docs, and typebox for runtime-validated TypeScript types.
Schema-First Validation
Fastify's plugin system is where it really shines. The @fastify/type-provider-typebox combination gives you a single source of truth: your TypeBox schema is both the TypeScript type and the runtime JSON Schema validator. Bad requests return structured 400 errors with specific field-level messages.
Route Organization
Keep route handlers thin. Each route file registers its own Fastify plugin, and the registered plugin contains the route definitions for that resource. Inversion of control is handled by Fastify's scoped plugin system.
Authentication and Testing
For JWT-based authentication, use @fastify/jwt and a simple preHandler hook. Fastify has an inject() method that lets you call route handlers without starting an actual HTTP server, making unit testing fast and reliable.
Performance Tips
Enable compression with @fastify/compress. Use the errorHandler plugin to standardize error responses. Set trust proxy correctly if you are behind a load balancer.