Starlette

Starlette is the production-ready, lightweight ASGI framework/toolkit for Python: it's your core engine for high-performance, asynchronous web services.

Starlette is the high-speed Python framework built on the ASGI standard, perfect for modern, asynchronous applications. It provides essential features: routing, middleware, WebSocket support, background tasks, and a robust `TestClient` (via `httpx`). This framework is famously the foundation for FastAPI, demonstrating its rock-solid, minimalist architecture. Use Starlette directly for a lean, high-performance service, or leverage its toolkit components for maximum flexibility. It delivers 100% test coverage and minimal hard dependencies, ensuring a clean, fast deployment pipeline.

https://www.starlette.io/