qmux

An implementation of the QMux protocol (draft-ietf-quic-qmux-00) for Rust and TypeScript.

QMux brings QUIC's multiplexed streams and datagrams to reliable, ordered byte-stream transports like TCP and WebSockets. It allows applications built for QUIC to seamlessly fall back to TCP/TLS when UDP is blocked by network middleboxes, without maintaining separate protocol implementations.

The protocol reuses QUIC frame types and semantics while adapting them for stream-based transports, providing multiplexed streams with flow control and optional unreliable datagrams.

Rust

[dependencies]
qmux = "0.0.1"

Features

tcp - QMux over raw TCP streams
tls - QMux over TLS (via tokio-rustls)
ws - QMux over WebSockets (via tokio-tungstenite)
wss - QMux over secure WebSockets (WebSocket + TLS)

Default features: tls, wss

TypeScript / JavaScript

npm install @moq/qmux

A WebTransport polyfill that uses WebSockets as the underlying transport. This allows WebTransport applications to work in environments where QUIC/UDP is unavailable, falling back to WebSocket with the QMux framing protocol.

import Qmux from "@moq/qmux"

// Use as a drop-in WebTransport replacement
const transport = new Qmux("https://example.com/endpoint")
await transport.ready

const stream = await transport.createBidirectionalStream()

Polyfill

Install as a global WebTransport polyfill:

import { install } from "@moq/qmux"

// Only installs if native WebTransport is unavailable
install()

// Now use the standard WebTransport API
const transport = new WebTransport("https://example.com/endpoint")

License