Python Web Servers: Uvicorn vs Gunicorn vs Daphne vs Hypercorn

When you're getting started with building and deploying web applications in Python, picking the right web server can really boost your app's performance, scalability, and compatibility. In the exciting world of asynchronous programming, it's super important to understand what makes servers like Uvicorn, Gunicorn, Daphne, and Hypercorn special. Let’s explore these options together!

In this blog post, we will explore each of these servers, their strengths and weaknesses, and when to use them.

What Are Python Web Servers?

Python web servers are responsible for handling HTTP requests and forwarding them to your application, then sending back the responses. Depending on the server, they might support different protocols (HTTP/1.1, HTTP/2), concurrency models (sync vs async), and interface standards (WSGI or ASGI).

Interface Standards: WSGI vs ASGI

ASGI is the modern alternative to WSGI, allowing support for long-lived connections and native async/await syntax in Python 3.7+.

WSGI vs ASGI Comparison

Standard	Stands For	Concurrency	WebSocket Support	Used By
WSGI	Web Server Gateway Interface	Synchronous only	No	Django, Flask
ASGI	Asynchronous Server Gateway Interface	Synchronous & Asynchronous	Yes	FastAPI, Starlette, Django Channels

1. Uvicorn

• Interface: ASGI
• Language: Python (built on uvloop and httptools)
• Async Support:  Yes
• WebSocket Support:  Yes

Best for: FastAPI, Starlette, async Django

Pros:

• Extremely fast and lightweight
• Designed for async-first frameworks
• Works great standalone or behind reverse proxies like Nginx

Example Usage:

uvicorn main:app --host 0.0.0.0 --port 8000 --workers 4​

2. Gunicorn

• Interface: WSGI (with optional ASGI via workers)
• Language: Python
• Async Support:  No (WSGI only)
• WebSocket Support:  No

Best for: Traditional Django and Flask apps

Pros:

• Mature and production-ready
• Battle-tested in many large deployments
• Supports multiple worker classes (sync, eventlet, gevent)

Cons:

• Does not natively support ASGI or async frameworks

Workaround:

gunicorn main:app -k uvicorn.workers.UvicornWorker​

This allows running FastAPI or other ASGI apps using Gunicorn's multi-process model with Uvicorn workers.

3. Daphne

• Interface: ASGI
• Language: Python (built on Twisted)
• Async Support:  Yes
• WebSocket Support:  Yes

Best for: Django Channels, real-time applications

Pros:

• First ASGI server ever created
• Officially supported by the Django Channels project

Cons:

• Slightly slower than Uvicorn and Hypercorn
• Twisted-based (may have a steeper learning curve for debugging)

Example Usage:

daphne myproject.asgi:application​

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4. Hypercorn

• Interface: ASGI / WSGI
• Language: Python (supports asyncio and trio)
• Async Support:  Yes
• WebSocket Support:  Yes

Best for: Developers needing flexibility across concurrency models and protocol versions

Pros:

• Supports HTTP/2, QUIC (experimental)
• Flexible backend choice: asyncio or trio
• Can serve both WSGI and ASGI apps

Cons:

• Slightly less popular than Uvicorn

Example Usage:

hypercorn main:app --bind 0.0.0.0:8000​

Feature Comparison Table

Feature	Uvicorn	Gunicorn	Daphne	Hypercorn
ASGI Support	Yes	No (needs workaround)	Yes	Yes
WSGI Support	No	Yes	No	Yes
Async/Await	Yes	No	Yes	Yes
WebSockets	Yes	No	Yes	Yes
HTTP/2	No	No	No	Yes
Performance	*****	***	***	****

Recommendation Summary

Use Case	Recommended Server
FastAPI / Starlette	Uvicorn
Traditional Django / Flask	Gunicorn
Django Channels / WebSockets	Daphne
HTTP/2, Experimental Protocols	Hypercorn
ASGI app behind Gunicorn	Gunicorn + UvicornWorker

Your choice of web server depends on the framework you're using, the nature of your application (sync vs async), and your deployment requirements (e.g., HTTP/2, WebSocket support).

In general:

• Use Uvicorn for modern async apps like FastAPI.
• Use Gunicorn for mature, sync-based apps like Django or Flask.
• Use Daphne if you're working with Django Channels and WebSockets.
• Use Hypercorn if you need a powerful ASGI server with broader protocol support.

Each server has its niche. Choose the one that fits your architecture best. Need help deploying? Reach out, and let’s build your backend the right way.