h3

h3 is a universal HTTP server framework for JavaScript and TypeScript, created by Pooya Parsa and built on top of web standards including the Fetch API, Web Streams, and Web Crypto. The framework serves as the foundational HTTP engine for the Nitro server toolkit and the Nuxt framework, powering applications deployed across millions of projects worldwide. h3 is runtime-agnostic, running natively on Node.js, Deno, Bun, Cloudflare Workers, Vercel Edge Functions, and any environment that supports web standard APIs, through the Srvx adapter layer that normalizes server implementations across runtimes. The core design emphasizes a tiny footprint with minimal dependencies, low request latency, and high composability through a system of tree-shakeable utility functions. The H3 class provides a fluent API with HTTP method routing through chained calls including .get, .post, .put, .patch, .delete, .head, .options, and .all, with support for dynamic route parameters, wildcards, and nested router instances. The handler API receives strongly-typed event objects containing the request, URL, headers, query parameters, body, and session data, with built-in utilities for reading request bodies, setting response headers, streaming responses, handling cookies, and managing server-sent events. The framework includes over 50 built-in utilities for response normalization, error handling with H3Error, CORS configuration, rate limiting, static file serving, and WebSocket support. Version 2 is currently in beta with a redesigned architecture. The project is sponsored by Vercel, VoidZero, and StackBlitz, with contributors including Daniel Roe, Anthony Fu, and Hebilicious.