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

|rtd| |pypi-v| |pypi-pyversions| |pypi-l| |pypi-wheel| |circleci| |codecov|

.. |rtd| image:: https://readthedocs.org/projects/websockets/badge/?version=latest
   :target: https://websockets.readthedocs.io/

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

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

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

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

.. |circleci| image:: https://img.shields.io/circleci/project/github/aaugustin/websockets.svg
   :target: https://circleci.com/gh/aaugustin/websockets

.. |codecov| image:: https://codecov.io/gh/aaugustin/websockets/branch/master/graph/badge.svg
    :target: https://codecov.io/gh/aaugustin/websockets

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

``websockets`` is a library for building WebSocket servers_ and clients_ in
Python with a focus on correctness and simplicity.

.. _servers: https://github.com/aaugustin/websockets/blob/master/example/server.py
.. _clients: https://github.com/aaugustin/websockets/blob/master/example/client.py

Built on top of ``asyncio``, Python's standard asynchronous I/O framework, it
provides an elegant coroutine-based API.

Here's how a client sends and receives messages:

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

.. code:: python

    #!/usr/bin/env python

    import asyncio
    import websockets

    async def hello(uri):
        async with websockets.connect(uri) as websocket:
            await websocket.send("Hello world!")
            await websocket.recv()

    asyncio.get_event_loop().run_until_complete(
        hello('ws://localhost:8765'))

And here's an echo server:

.. code:: python

    #!/usr/bin/env python

    import asyncio
    import websockets

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

    asyncio.get_event_loop().run_until_complete(
        websockets.serve(echo, 'localhost', 8765))
    asyncio.get_event_loop().run_forever()

Does that look good?

`Start here!`_

.. _Start here!: https://websockets.readthedocs.io/en/stable/intro.html

Why should I use ``websockets``?
--------------------------------

The development of ``websockets`` is shaped by four principles:

1. **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.

2. **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.

3. **Quality**: ``websockets`` is heavily tested. Continuous integration fails
   under 100% branch coverage. Also it passes the industry-standard `Autobahn
   Testsuite`_.

4. **Performance**: memory use is configurable. An extension written in C
   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.

Professional support is available if you — or your company — are so inclined.
`Get in touch`_.

(If you contribute to ``websockets`` and would like to become an official
support provider, let me know.)

.. _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
.. _Autobahn Testsuite: https://github.com/aaugustin/websockets/blob/master/compliance/README.rst
.. _Get in touch: https://fractalideas.com/

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 a HTTP health check.
* If you want to use Python 2: ``websockets`` builds upon ``asyncio`` which
  only works on Python 3. ``websockets`` requires Python ≥ 3.6.

What else?
----------

Bug reports, patches and suggestions are welcome!

Please open an issue_ or send a `pull request`_.

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

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

.. _Contributor Covenant code of conduct: https://github.com/aaugustin/websockets/blob/master/CODE_OF_CONDUCT.md

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

.. _BSD license: https://github.com/aaugustin/websockets/blob/master/LICENSE