Granian

Granian is a Rust-based HTTP server for Python applications, built on top of Hyper and Tokio. It provides a single, self-contained dependency to serve ASGI, WSGI, and its own RSGI interface applications, replacing the usual Gunicorn + Uvicorn + http-tools stack.

Designed around a correct, unified HTTP implementation, Granian supports HTTP/1 and HTTP/2, HTTPS and mTLS, websockets, and direct static-file serving, with strong concurrency characteristics and high throughput across Linux, macOS, and Windows.

What You Get

• A single-dependency HTTP server binary distributed as a Python wheel for Linux, macOS, and Windows
• Support for ASGI/3, WSGI, and the native RSGI application interfaces
• HTTP/1 and HTTP/2 protocols with HTTPS and mTLS support
• Websockets and direct static-file serving out of the box
• A configurable CLI plus an embeddable Server API for programmatic control

Common Use Cases

• Serving FastAPI, Starlette, Django, or Flask applications in production
• Replacing a Gunicorn + Uvicorn worker setup with one dependency
• Serving Python apps over HTTP/2 with high throughput and websockets
• Running applications with mTLS or direct static-file delivery

Under The Hood

Architecture - Granian splits responsibilities across a Rust core (src/lib.rs, serve.rs, workers.rs, http.rs, ws.rs, tls.rs) that owns the HTTP/1 and HTTP/2 handling on top of Hyper and Tokio, and a thin Python layer (granian/server, granian/asgi.py, wsgi.py, rsgi.py, cli.py) that bridges incoming requests into the ASGI, WSGI, or RSGI callable and manages the worker process model.

Tech Stack - The server core is written in Rust using Hyper and Tokio and compiled into a Python extension via PyO3/maturin; the Python side depends only on click for its CLI, with optional extras for dotenv, process naming, reload, and alternative event loops (rloop, uvloop, winloop).

Code Quality - The repository ships a substantial pytest suite (test_asgi.py, test_wsgi.py, test_rsgi.py, test_ws.py, test_https.py, test_static_files.py, test_uds.py, and more) covering each interface and transport, alongside typed Python (py.typed, _granian.pyi stubs) and a modular Rust source tree, indicating a mature, well-tested codebase.

API Design - Usage centers on a single ergonomic CLI (granian —interface asgi main:app) with an embeddable Server class for programmatic control; configuration is exposed through well-named flags and options, and the documented ASGI/WSGI/RSGI contracts keep onboarding for existing Python web apps minimal.