API reference

Features

Check which implementations support which features and known limitations.

• Features

asyncio

It’s ideal for servers that handle many clients concurrently.

This is the default implementation.

• Server (asyncio)
• Client (asyncio)

threading

This alternative implementation can be a good choice for clients.

• Server (threading)
• Client (threading)

Sans-I/O

This layer is designed for integrating in third-party libraries, typically application servers.

• Server (Sans-I/O)
• Client (Sans-I/O)

Legacy

This is the historical implementation. It is deprecated. It will be removed by 2030.

• Server (legacy)
• Client (legacy)

Extensions

The Per-Message Deflate extension is built-in. You may also define custom extensions.

• Extensions

Shared

These low-level APIs are shared by all implementations.

• Data structures
• Exceptions
• Types
• Environment variables

API stability

Public APIs documented in this API reference are subject to the backwards-compatibility policy.

Anything that isn’t listed in the API reference is a private API. There’s no guarantees of behavior or backwards-compatibility for private APIs.

Convenience imports

For convenience, some public APIs can be imported directly from the websockets package.