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Async binding for Tungstenite, the Lightweight stream-based WebSocket implementation


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Asynchronous WebSockets for async-std, tokio, gio and any std Futures runtime.

MIT licensed Build Status



Add this in your Cargo.toml:

async-tungstenite = "*"

Take a look at the examples/ directory for client and server examples. You may also want to get familiar with async-std or tokio if you don't have any experience with it.

What is async-tungstenite?

This crate is based on tungstenite Rust WebSocket library and provides async bindings and wrappers for it, so you can use it with non-blocking/asynchronous TcpStreams from and couple it together with other crates from the async stack. In addition, optional integration with various other crates can be enabled via feature flags

  • async-tls: Enables the async_tls module, which provides integration with the async-tls TLS stack and can be used independent of any async runtime.
  • async-std-runtime: Enables the async_std module, which provides integration with the async-std runtime.
  • async-native-tls: Enables the additional functions in the async_std module to implement TLS via async-native-tls.
  • tokio-runtime: Enables the tokio module, which provides integration with the tokio runtime.
  • tokio-native-tls: Enables the additional functions in the tokio module to implement TLS via tokio-native-tls.
  • tokio-rustls-native-certs: Enables the additional functions in the tokio module to implement TLS via tokio-rustls and uses native system certificates found with rustls-native-certs.
  • tokio-rustls-webpki-roots: Enables the additional functions in the tokio module to implement TLS via tokio-rustls and uses the certificates webpki-roots provides.
  • gio-runtime: Enables the gio module, which provides integration with the gio runtime.

Messages vs Streaming

WebSocket provides a message-oriented protocol, and this crate supports sending and receiving data in messages; protocols built on WebSocket are allowed to make message boundaries semantically significant. However, some users of WebSocket may want to treat the socket as a continuous stream of bytes. If you know the sending end does not place significance on message boundaries, and you want to process a stream of bytes without regard to those boundaries, try ws_stream_tungstenite, which builds upon this crate.

Is it performant?

In essence, async-tungstenite is a wrapper for tungstenite, so the performance is capped by the performance of tungstenite. tungstenite has a decent performance (it has been used in production for real-time communication software, video conferencing, etc), but it's definitely not the fastest WebSocket library in the world at the moment of writing this note.

If performance is of a paramount importance for you (especially if you send large messages), then you might want to check other libraries that have been designed to be performant or you could file a PR against tungstenite to improve the performance!

We are aware of changes that both tungstenite and async-tungstenite need in order to fill the gap of ~30% performance difference between tungstenite and more performant libraries like fastwebsockets, but we have not worked on that yet as it was not required for the use case that original authors designed the library for. In the course of past years we have merged several performance improvements submitted by the awesome community of Rust users who helped to improve the library! For a quick summary of the pending performance problems/improvements, see the comment.


Originally this crate was created as a fork of tokio-tungstenite and ported to the traits of the futures crate. Integration into async-std, tokio and gio was added on top of that.