API Reference

This reference documents every public symbol in both languages: the signature as the source declares it, every parameter, the return value, the exceptions raised, and one runnable example. The test suite executes the examples; an example that fails fails the build.

Conventions used on every page:

• Durations state their unit. Python takes seconds as floats (timeout=5.0); TypeScript takes milliseconds as integers ({ timeoutMs: 5000 }). The two ports use the same names otherwise, in each language's casing: on_stream / onStream, is_open / isOpen.
• Limits are local to the peer that sets them. max_payload_bytes, max_concurrent_streams and error_serializer are configured per connection and are never sent to or negotiated with the remote. The remote observes a limit only as the reset it receives when it exceeds the limit.
• muxws/node re-exports part of muxws. Reconnect, ReconnectOptions, Hello, HelloOptions, ConnectOptions, backoffDelay, shouldRetry, unjitteredDelay, PeerRegistry, TagValue and VERSION are exported from both entry points. WsSocket is exported from muxws/node only; no module reachable from muxws may import it (WSM-API-022). The codecs, the errors, Peer and the frame helpers are exported from muxws only, and importing muxws registers the JSON codec.

The Python package requires Python 3.10 or newer. The websockets extra requires websockets 14 or newer, the first release whose top-level connect is websockets.asyncio.client.connect, which takes additional_headers.

The pages

Page	What it covers
connect	Dialling a peer, in Python, in the browser and under Node, with every connection option.
accept	The acceptor side: accept, serve, and the subprotocol hooks that refuse a codec you do not speak.
Peer	The object both ends hold: opening streams, the handler and lifecycle callbacks, header interceptors, ping, close, serve.
Stream	One call: sending, ending, replying, awaiting, iterating, cancelling and resetting.
Reconnect	The dialer-only helper: backoff, the hello, and the three functions that compute its schedule.
Errors	The exception tree, the nine reset codes, and how a reset becomes an exception.
Codec	The codec protocol, the two codecs that ship, the registry, and the settings that select one.
Registry	PeerRegistry: tagging live peers and looking them up again.
Transports	SocketAdapter and every adapter that implements it, in both languages, plus the ws+unix: URL grammar and the websockets dial gates.
Types	Frame and its envelope, the frame helpers, CloseReason, the two callback aliases and the three interceptor aliases.

For an introduction, see the rationale and the quick start. This reference assumes an open connection.