API Frameworks

5 open source tools compared. Sorted by stars — scroll down for our analysis.

Tool	Stars	Velocity	Language	License	Score
FastAPI High performance Python web framework, ready for production	96.6k	—	Python	MIT License	82
NestJS Progressive Node.js framework for scalable server-side apps	75.0k	—	TypeScript	MIT License	82
Express Fast, unopinionated, minimalist web framework for Node	68.9k	—	JavaScript	MIT License	82
Hono Web framework built on Web Standards	29.5k	+126/wk	TypeScript	MIT License	77
Elysia Ergonomic framework for Bun and Web Standards	17.7k	+88/wk	TypeScript	MIT License	77

Our Analysis

FastAPI96.6k★

FastAPI is the Python web framework that made everyone realize Flask was holding them back. Async-native, automatic OpenAPI docs, Pydantic validation built in, and 15-20k requests per second on Uvicorn. It handles 2-5x the throughput of Flask on identical hardware. Django is the batteries-included monolith — admin panel, ORM, auth, all pre-built. Flask is minimalist but synchronous and showing its age. For building APIs specifically, FastAPI wins on speed, type safety, and developer experience. Use FastAPI if you're building a REST or GraphQL API, especially one that talks to LLMs, external services, or anything I/O-heavy where async matters. If you need a full web app with templates, admin, and ORM, Django is still the pragmatic choice. The catch: FastAPI is an API framework, not a web framework. No built-in admin, no ORM, no template engine. You'll assemble those yourself. And one synchronous ORM call will block the event loop and tank your performance — you need async-compatible libraries throughout your entire stack.

NestJS75.0k★

NestJS is the backend framework for TypeScript developers who miss having structure. Decorators, dependency injection, modules, guards, interceptors — it's Angular's architecture applied to server-side Node.js. Opinionated in the way that saves you from making bad decisions. If you're building a non-trivial API and Express feels like building with no guardrails, NestJS provides the architecture. Express is the minimal baseline. Fastify is faster but equally unopinionated. Hono is the new lightweight contender. AdonisJS is the other full-featured option. Spring Boot is the Java equivalent NestJS clearly borrowed from. Best for teams building production APIs who want conventions, not chaos. The module system and DI container make large codebases manageable. TypeScript support is first-class — it was built for it. The catch: the decorator-heavy style is love-it-or-hate-it. The abstraction layers add overhead — both mental and runtime. Simple APIs feel over-engineered in NestJS. And if you're a solo founder building fast, Express + a few libraries might get you to MVP quicker than learning NestJS's patterns.

Express68.9k★

Express is the Honda Civic of Node.js frameworks — it's everywhere, it works, and nobody's excited about it anymore. At 68k stars and 14 years old, it's the most deployed Node.js framework in existence. Every tutorial, every boilerplate, every Stack Overflow answer assumes Express. Fastify is 2-3x faster with built-in schema validation and JSON serialization. Hono is the new generation — TypeScript-first, runs on every edge runtime (Cloudflare Workers, Deno, Bun, Lambda), and its same-code-everywhere promise is genuinely compelling. Both are better technical choices for new projects. Use Express if your team knows it, your codebase already uses it, or you need maximum library compatibility. The middleware ecosystem is unmatched. The catch: Express is synchronous by design and shows its age. No built-in TypeScript support, no schema validation, no structured error handling. Express 5 has been "coming soon" for years. For new projects in 2026, starting with Fastify or Hono is the forward-looking choice — Express is for maintaining what already exists.

Hono29.5k★

Hono is the web framework built on Web Standards — your code runs on Cloudflare Workers, Deno, Bun, AWS Lambda, Vercel Edge, and Node.js without changing a line. A 7.6KB gzipped bundle with 2.8M weekly downloads (up 340% year-over-year) and growing fast. The Fetch API foundation means no Node.js-specific abstractions to learn or unlearn. Middleware ecosystem is solid: JWT, CORS, rate limiting, OpenAPI docs. Compared to Express (legacy, 65% market share but showing age), Hono is modern and portable. Compared to Fastify (faster on Node.js specifically), Hono runs everywhere. Compared to Elysia (Bun-optimized, newer), Hono has more runtime support and community. Use this when you're building APIs that might deploy to edge runtimes, serverless functions, or multiple platforms. Also great for Cloudflare Workers where bundle size matters. Skip this if you need Express's massive middleware ecosystem or Fastify's raw Node.js throughput. The catch: "runs everywhere" means testing everywhere too. Edge runtime limitations (no filesystem, no native modules) constrain what you can do. And the Web Standards foundation means some Node.js libraries won't work directly. MIT license.

Elysia17.7k★

Elysia is what happens when you build a web framework specifically for Bun and stop caring about Node.js compatibility. The result: 2.5M requests per second, end-to-end type safety between server and client via Eden (no codegen), and an API that makes Express feel like writing COBOL. If you're building APIs on Bun and want the fastest possible framework with TypeScript-native ergonomics, Elysia is it. Hono is the portable alternative — same code runs on Cloudflare Workers, Deno, Bun, and Node — but it's slower on Bun and lacks Eden's type-safe client. Express has 30M weekly downloads and no excuse to still exist in new projects. Fastify is the mature Node.js option. The catch: Elysia means Bun. Not "Bun optional" — Bun required in production. That's a runtime bet most teams aren't ready to make. If Bun hits a bug in your deployment, your framework can't save you. And with 500K weekly downloads versus Hono's 1.8M, the ecosystem and hiring pool are significantly smaller.