Aiohttp

Aiohttp is an asynchronous HTTP client and server framework for Python, built on top of asyncio. Developed by Andrew Svetlov and the aio-libs team since 2013, it provides both a high-level client API for making HTTP requests and a complete web server framework comparable to Flask or FastAPI, but fully asynchronous. The client supports HTTP/1.1, HTTP/2, WebSocket (both client and server), connection pooling, multipart file uploads, cookie handling, SSL/TLS with custom contexts, proxy support (HTTP, HTTPS, SOCKS), and streaming responses for memory-efficient large file handling. The server framework includes: URL routing with resources and dynamic routes, middleware support for cross-cutting concerns (authentication, logging, CORS), request handlers with type hints, Jinja2 template integration, static file serving, session management, and WebSocket bidirectional communication. Performance benchmarks show aiohttp handling over 60,000 HTTP requests per second on a single core for simple endpoints. The library is used as the HTTP layer by major Python projects including Discord.py (Discord bot framework), Motor (async MongoDB driver), and aiogram (Telegram bot framework). As of 2026, aiohttp version 3.10+ has over 15,200 stars and is downloaded over 300 million times per month from PyPI.