Fastify

Fastify is a high-performance open-source web framework for Node.js created by Matteo Collina and Tomas Della Vedova in 2016, focused on providing the best developer experience with the lowest overhead, benchmarking as one of the fastest Node.js web frameworks capable of handling over seventy-six thousand requests per second, adopted by companies including Microsoft, AWS, Google, and Auth0 for high-throughput API services. The performance optimization is achieved through a highly optimized routing engine based on a radix tree data structure that enables O(1) route lookup, JSON schema-based serialization that pre-compiles response serializers at startup for dramatic throughput improvements, and minimal middleware overhead through a hook-based lifecycle architecture that avoids the overhead of traditional Express middleware chains. The schema validation uses JSON Schema to validate request inputs and serialize responses, with the framework automatically generating fast validation and serialization functions at startup using Ajv, resulting in JSON responses serialized up to two to three times faster than JSON dot stringify, while providing automatic TypeScript type inference from schemas for type-safe request and response handling. The plugin architecture provides an encapsulated context system where plugins can share functionality through decorators, hooks, and encapsulated scopes, enabling modular application composition with automatic loading and dependency ordering, with the official ecosystem providing plugins for database connections, authentication, rate limiting, CORS, static file serving, WebSocket, and more. The TypeScript support provides first-class type definitions with automatic inference from route schemas. The logging integrates with Pino for high-performance structured logging. The request lifecycle hooks enable pre-handler, on-request, and on-response interception. Designed for backend developers building high-performance APIs.