What is websockets?

websockets is a library for building WebSocket servers and clients in Python with a focus on correctness, simplicity, robustness, and performance.

Built on top of asyncio, Python’s standard asynchronous I/O framework, the default implementation provides an elegant coroutine-based API.

An implementation on top of threading and a Sans-I/O implementation are also available.

Documentation is available on Read the Docs.

Here’s an echo server with the asyncio API:

#!/usr/bin/env python

import asyncio
from websockets.asyncio.server import serve

async def echo(websocket):
    async for message in websocket:
        await websocket.send(message)

async def main():
    async with serve(echo, "localhost", 8765) as server:
        await server.serve_forever()

asyncio.run(main())

Here’s how a client sends and receives messages with the threading API:

#!/usr/bin/env python

from websockets.sync.client import connect

def hello():
    with connect("ws://localhost:8765") as websocket:
        websocket.send("Hello world!")
        message = websocket.recv()
        print(f"Received: {message}")

hello()

Does that look good?

Get started with the tutorial!

Why should I use websockets?

The development of websockets is shaped by four principles:

1. Correctness: websockets is heavily tested for compliance with RFC 6455. Continuous integration fails under 100% branch coverage.

2. Simplicity: all you need to understand is msg = await ws.recv() and await ws.send(msg). websockets takes care of managing connections so you can focus on your application.

3. Robustness: websockets is built for production. For example, it was the only library to handle backpressure correctly before the issue became widely known in the Python community.

4. Performance: memory usage is optimized and configurable. A C extension accelerates expensive operations. It’s pre-compiled for Linux, macOS and Windows and packaged in the wheel format for each system and Python version.

Documentation is a first class concern in the project. Head over to Read the Docs and see for yourself.

Why shouldn’t I use websockets?

• If you prefer callbacks over coroutines: websockets was created to provide the best coroutine-based API to manage WebSocket connections in Python. Pick another library for a callback-based API.

• If you’re looking for a mixed HTTP / WebSocket library: websockets aims at being an excellent implementation of RFC 6455: The WebSocket Protocol and RFC 7692: Compression Extensions for WebSocket. Its support for HTTP is minimal — just enough for an HTTP health check.

  If you want to do both in the same server, look at HTTP + WebSocket servers that build on top of websockets to support WebSocket connections, like uvicorn or Sanic.

What else?

Bug reports, patches and suggestions are welcome!

To report a security vulnerability, please use the Tidelift security contact. Tidelift will coordinate the fix and disclosure.

For anything else, please open an issue or send a pull request.

Participants must uphold the Contributor Covenant code of conduct.

websockets is released under the BSD license.