websockets 16.0
An implementation of the WebSocket Protocol (RFC 6455 & 7692)
Requires Python: >=3.10
Keywords: WebSocket

.. image:: logo/horizontal.svg
   :width: 480px
   :alt: websockets

|licence| |version| |pyversions| |tests| |docs| |openssf|

.. |licence| image:: https://img.shields.io/pypi/l/websockets.svg
    :target: https://pypi.python.org/pypi/websockets

.. |version| image:: https://img.shields.io/pypi/v/websockets.svg
    :target: https://pypi.python.org/pypi/websockets

.. |pyversions| image:: https://img.shields.io/pypi/pyversions/websockets.svg
    :target: https://pypi.python.org/pypi/websockets

.. |tests| image:: https://img.shields.io/github/checks-status/python-websockets/websockets/main?label=tests
   :target: https://github.com/python-websockets/websockets/actions/workflows/tests.yml

.. |docs| image:: https://img.shields.io/readthedocs/websockets.svg
   :target: https://websockets.readthedocs.io/

.. |openssf| image:: https://bestpractices.coreinfrastructure.org/projects/6475/badge
   :target: https://bestpractices.coreinfrastructure.org/projects/6475

What is ``websockets``?
-----------------------

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

.. _WebSocket: https://developer.mozilla.org/en-US/docs/Web/API/WebSockets_API

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. <https://websockets.readthedocs.io/>`_

.. copy-pasted because GitHub doesn't support the include directive

Here's an echo server with the ``asyncio`` API:

.. code:: python

    #!/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:

.. code:: python

    #!/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! <https://websockets.readthedocs.io/en/stable/intro/index.html>`_

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.

.. _Read the Docs: https://websockets.readthedocs.io/
.. _handle backpressure correctly: https://vorpus.org/blog/some-thoughts-on-asynchronous-api-design-in-a-post-asyncawait-world/#websocket-servers

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_.

.. _uvicorn: https://www.uvicorn.org/
.. _Sanic: https://sanic.dev/en/

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.

.. _Tidelift security contact: https://tidelift.com/security

For anything else, please open an issue_ or send a `pull request`_.

.. _issue: https://github.com/python-websockets/websockets/issues/new
.. _pull request: https://github.com/python-websockets/websockets/compare/

Participants must uphold the `Contributor Covenant code of conduct`_.

.. _Contributor Covenant code of conduct: https://github.com/python-websockets/websockets/blob/main/CODE_OF_CONDUCT.md

``websockets`` is released under the `BSD license`_.

.. _BSD license: https://github.com/python-websockets/websockets/blob/main/LICENSE