websockets is a library for building WebSocket servers and clients in Python with a focus on correctness, simplicity, robustness, and performance. It supports several network I/O and control flow paradigms. The default implementation builds upon asyncio, Python’s built-in asynchronous I/O library. It provides an elegant coroutine-based API. It’s ideal for servers that handle many client connections. The threading implementation is a good alternative for clients, especially if you aren’t familiar with asyncio. It may also be used for servers that handle few client connections. The Sans-I/O implementation is designed for integrating in third-party libraries, typically application servers, in addition being used internally by websockets.