The WebSocket API is an advanced technology that makes it possible to open a two-way interactive communication session between the user's browser and a server. With this API, you can send messages to a server and receive event-driven responses without having to poll the server for a reply.
Note: While a WebSocket connection is functionally somewhat similar to standard Unix-style sockets, they are not related.
Interfaces
WebSocket- The primary interface for connecting to a WebSocket server and then sending and receiving data on the connection.
CloseEvent- The event sent by the WebSocket object when the connection closes.
MessageEvent- The event sent by the WebSocket object when a message is received from the server.
Tools
- HumbleNet: A cross-platform networking library that works in the browser. It consists of a C wrapper around WebSockets and WebRTC that abstracts away cross-browser differences, facilitating the creation of multi-user networking functionality for games and other apps.
- µWebSockets: Highly scalable WebSocket server and client implementation for C++11 and Node.js.
- ClusterWS: Lightweight, fast and powerful framework for building scalable WebSocket applications in Node.js.
- Socket.IO: A long polling/WebSocket based third party transfer protocol for Node.js.
- SocketCluster: A pub/sub WebSocket framework for Node.js with a focus on scalability.
- WebSocket-Node: A WebSocket server API implementation for Node.js.
- Total.js: Web application framework for Node.js (Example: WebSocket chat)
- Faye: A WebSocket (two-ways connections) and EventSource (one-way connections) for Node.js Server and Client.
- SignalR: SignalR will use WebSockets under the covers when it's available, and gracefully fallback to other techniques and technologies when it isn't, while your application code stays the same.
- Caddy: A web server capable of proxying arbitrary commands (stdin/stdout) as a websocket.
- ws: a popular WebSocket client & server library for Node.js.
- jsonrpc-bidirectional: Easy to use asynchronous RPC library with bidirectional calls support over a single WebSocket or RTCDataChannel (WebRTC) connection. The TCP/SCTP/etc. client and server may each host its own JSONRPC.Server endpoint at the same time.
- rpc-websockets: JSON-RPC 2.0 implementation over WebSockets for Node.js and JavaScript.
Related Topics
See also
Browser compatibility
We're converting our compatibility data into a machine-readable JSON format. This compatibility table still uses the old format, because we haven't yet converted the data it contains. Find out how you can help!
| Feature | Chrome | Edge | Firefox (Gecko) | Internet Explorer | Opera | Safari |
|---|---|---|---|---|---|---|
| Version -76 support | 6 | No support | 4.0 (2.0) | No support | 11.00 (disabled) | 5.0.1 |
| Protocol version 7 support | No support | No support | 6.0 (6.0) Moz |
No support | No support | No support |
| Protocol version 10 support | 14 | No support | 7.0 (7.0) Moz |
HTML5 Labs | ? | ? |
| Standard - RFC 6455 Support | 43 | 14 | 48.0 (48.0) | 10 | 12.10 | 6.0 |
| Usable in Workers | (Yes) | (Yes) | 37.0 (37.0) | ? | ? | ? |
| Feature | Android | Edge | Firefox Mobile (Gecko) | IE Mobile | Opera Mobile | Safari Mobile |
|---|---|---|---|---|---|---|
| Version -76 support | ? | No support | ? | ? | ? | ? |
| Protocol version 7 support | ? | No support | ? | ? | ? | ? |
| Protocol version 8 support (IETF draft 10) | ? | No support | 7.0 (7.0) | ? | ? | ? |
| Standard - RFC 6455 Support | 4.4 | (Yes) | 11.0 (11.0) | ? | 12.10 | 6.0 |
| Usable in Workers | (Yes) | (Yes) | 37.0 (37.0) | ? | ? | ? |
Gecko notes
WebSockets support in Firefox is continuing to track the evolving WebSocket specification. Firefox 6 implements version 7 of the underlying protocol, while Firefox 7 implements version 8 (as specified by IETF draft 10). Firefox mobile received WebSocket support in Firefox mobile 7.0.
Gecko 6.0
Prior to Gecko 6.0 (Firefox 6.0 / Thunderbird 6.0 / SeaMonkey 2.3), there was, incorrectly, a WebSocket object that some sites were thinking implied that WebSocket services were not prefixed; this object has been renamed to MozWebSocket.
Gecko 7.0
Starting in Gecko 7.0 (Firefox 7.0 / Thunderbird 7.0 / SeaMonkey 2.4), the network.websocket.max-connections preference is used to determine the maximum number of WebSocket connections that can be open at a time. The default value is 200.
Gecko 8.0
Starting in Gecko 8.0 (Firefox 8.0 / Thunderbird 8.0 / SeaMonkey 2.5), the deflate-stream extension to the WebSocket protocol has been disabled, since it's been deprecated from the specification drafts. This resolves incompatibilities with some sites.
Gecko 11.0
Prior to Gecko 11.0, both incoming and outgoing messages were limited to 16 MB in size. They may now be up to 2 GB in size. Note, however, that memory limitations (especially on mobile devices) make that a theoretical maximum, not a practical one. In reality, transfers of that size will fail on devices that don't have enough memory.
Additionally, ArrayBuffer send and receive support for binary data has been implemented.
Starting in Gecko 11.0, the WebSocket API is no longer prefixed.