Python / Uvicorn Fundamentals Interview Questions
What is the difference between Uvicorn, Hypercorn, and Daphne as ASGI servers?
Several ASGI server implementations exist. Uvicorn is the most widely used, but Hypercorn and Daphne are also production-ready alternatives with different strengths.
| Feature | Uvicorn | Hypercorn | Daphne |
|---|---|---|---|
| HTTP/1.1 | Yes | Yes | Yes |
| HTTP/2 | No | Yes | Yes |
| HTTP/3 | No | Yes | No |
| WebSockets | Yes | Yes | Yes |
| Python async | asyncio / uvloop | asyncio / uvloop / trio | asyncio |
| Process management | Via Gunicorn | Built-in | Via Gunicorn |
| Origin | Encode (Tom Christie) | Pallets project | Django/Channels team |
| Best for | FastAPI, Starlette, general ASGI | HTTP/2 needs, Quart apps | Django Channels |
When to choose each:
- Uvicorn - the default choice for FastAPI and Starlette; best performance for HTTP/1.1 + WebSocket workloads; most documentation and community support
- Hypercorn - choose when you need HTTP/2 or HTTP/3 support natively (without a proxy layer), or if your app uses the Quart framework (Hypercorn was originally Quart's server)
- Daphne - the original ASGI server; choose for Django Channels applications where it has the best compatibility
Which ASGI server natively supports HTTP/3 in addition to HTTP/1.1 and HTTP/2?
For a new FastAPI application, which ASGI server is the recommended default choice?
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