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.

Guides

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.
  • CWS: Fast C++ WebSocket implementation for Node.js (uWebSockets v0.14 fork)
  • 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: Asynchronous RPC which, on a single connection, may have functions exported on the server and, and the same time, on the client (client may call server, server may also call client).
  • cowboy: Cowboy is a small, fast and modern HTTP server for Erlang/OTP with WebSocket support.

Related Topics

Specifications

Specification Status Comments
HTML Living StandardThe definition of 'WebSocket API' in that specification. Living Standard
WebSockets Candidate Recommendation
RFC 6455: The WebSocket Protocol IETF RFC

Browser compatibility

Update compatibility data on GitHub

Desktop Mobile
Chrome Edge Firefox Internet Explorer Opera Safari Android webview Chrome for Android Firefox for Android Opera for Android Safari on iOS Samsung Internet
WebSocket Chrome

Full support 4

Edge

Full support 12

Firefox Full support 11


Full support 11


No support 7 — 11

Prefixed' Notes'

Prefixed' Implemented with the vendor prefix: Moz Notes' Message size limited to 16 MB (see bug 711205). No support 4 — 6

Notes'

Notes' Message size limited to 16 MB (see bug 711205).

IE

Full support 10

Opera

Full support 12.1

Safari

Full support 5

WebView Android

Full support ≤37

Chrome Android

Full support 18

Firefox Android Full support 14

Notes'

Full support 14

Notes'

Notes' See bug 695635. No support 7 — 14

Prefixed' Notes'

Prefixed' Implemented with the vendor prefix: Moz Notes' Message size limited to 16 MB (see bug 711205). No support 4 — 6

Notes'

Notes' Message size limited to 16 MB (see bug 711205).

Opera Android

Full support 12.1

Safari iOS

Full support 4.2

Samsung Internet Android

Full support 1.0

WebSocket() constructor Chrome

Full support Yes

Edge

Full support ≤79

Firefox Full support 7


Full support 7


No support 4 — 7

Notes'

Notes' Parameter protocols not supported.

IE

?

Opera

Full support Yes

Safari

?

WebView Android

Full support Yes

Chrome Android

Full support Yes

Firefox Android

Full support 7

Opera Android

?

Safari iOS

?

Samsung Internet Android

Full support Yes

binaryType Chrome

Full support Yes

Edge

Full support 12

Firefox

Full support Yes

IE

?

Opera

Full support Yes

Safari

Full support Yes

WebView Android

Full support Yes

Chrome Android

Full support Yes

Firefox Android

Full support Yes

Opera Android

Full support Yes

Safari iOS

Full support Yes

Samsung Internet Android

Full support Yes

bufferedAmount Chrome

Full support Yes

Edge

Full support 12

Firefox

Full support Yes

IE

?

Opera

Full support Yes

Safari

Full support Yes

WebView Android

Full support Yes

Chrome Android

Full support Yes

Firefox Android

Full support Yes

Opera Android

Full support Yes

Safari iOS

Full support Yes

Samsung Internet Android

Full support Yes

close Chrome

Full support 4

Edge

Full support 12

Firefox Full support 8


Full support 8


No support 4 — 8

Notes'

Notes' Parameters not supported, see bug 674716.

IE

Full support 10

Opera

Full support 12.1

Safari

Full support 5

WebView Android

Full support ≤37

Chrome Android

Full support 18

Firefox Android Full support 8


Full support 8


No support 4 — 8

Notes'

Notes' Parameters not supported, see bug 674716.

Opera Android

Full support 12.1

Safari iOS

Full support 4.2

Samsung Internet Android

Full support 1.0

close event Chrome

Full support Yes

Edge

Full support 12

Firefox

Full support Yes

IE

?

Opera

Full support Yes

Safari

?

WebView Android

Full support Yes

Chrome Android

Full support Yes

Firefox Android

Full support Yes

Opera Android

?

Safari iOS

?

Samsung Internet Android

Full support Yes

error event Chrome

Full support Yes

Edge

Full support 12

Firefox

Full support Yes

IE

?

Opera

Full support Yes

Safari

?

WebView Android

Full support Yes

Chrome Android

Full support Yes

Firefox Android

Full support Yes

Opera Android

?

Safari iOS

?

Samsung Internet Android

Full support Yes

extensions Chrome

Full support Yes

Edge

Full support 12

Firefox

Full support 8

IE

?

Opera

Full support Yes

Safari

Full support Yes

WebView Android

Full support Yes

Chrome Android

Full support Yes

Firefox Android

Full support 8

Opera Android

Full support Yes

Safari iOS

Full support Yes

Samsung Internet Android

Full support Yes

message event Chrome

Full support Yes

Edge

Full support 12

Firefox

Full support Yes

IE

?

Opera

Full support Yes

Safari

?

WebView Android

Full support Yes

Chrome Android

Full support Yes

Firefox Android

Full support Yes

Opera Android

?

Safari iOS

?

Samsung Internet Android

Full support Yes

onclose Chrome

Full support Yes

Edge

Full support 12

Firefox

Full support Yes

IE

?

Opera

Full support Yes

Safari

Full support Yes

WebView Android

Full support Yes

Chrome Android

Full support Yes

Firefox Android

Full support Yes

Opera Android

Full support Yes

Safari iOS

Full support Yes

Samsung Internet Android

Full support Yes

onerror Chrome

Full support Yes

Edge

Full support 12

Firefox

Full support Yes

IE

?

Opera

Full support Yes

Safari

Full support Yes

WebView Android

Full support Yes

Chrome Android

Full support Yes

Firefox Android

Full support Yes

Opera Android

Full support Yes

Safari iOS

Full support Yes

Samsung Internet Android

Full support Yes

onmessage Chrome

Full support Yes

Edge

Full support 12

Firefox

Full support Yes

IE

?

Opera

Full support Yes

Safari

Full support Yes

WebView Android

Full support Yes

Chrome Android

Full support Yes

Firefox Android

Full support Yes

Opera Android

Full support Yes

Safari iOS

Full support Yes

Samsung Internet Android

Full support Yes

onopen Chrome

Full support Yes

Edge

Full support 12

Firefox

Full support Yes

IE

?

Opera

Full support Yes

Safari

Full support Yes

WebView Android

Full support Yes

Chrome Android

Full support Yes

Firefox Android

Full support Yes

Opera Android

Full support Yes

Safari iOS

Full support Yes

Samsung Internet Android

Full support Yes

open event Chrome

Full support Yes

Edge

Full support 12

Firefox

Full support Yes

IE

?

Opera

Full support Yes

Safari

?

WebView Android

Full support Yes

Chrome Android

Full support Yes

Firefox Android

Full support Yes

Opera Android

?

Safari iOS

?

Samsung Internet Android

Full support Yes

protocol Chrome

Full support Yes

Edge

Full support 12

Firefox

Full support Yes

IE

?

Opera

Full support Yes

Safari

Full support Yes

WebView Android

Full support Yes

Chrome Android

Full support Yes

Firefox Android

Full support Yes

Opera Android

Full support Yes

Safari iOS

Full support Yes

Samsung Internet Android

Full support Yes

Supports protocol as specified by RFC 6455 Chrome

Full support 16

Edge

Full support 12

Firefox

Full support 11

IE

Full support 10

Opera

Full support 15

Safari

Full support 6

WebView Android

Full support Yes

Chrome Android

Full support 18

Firefox Android

Full support 14

Opera Android

Full support 14

Safari iOS

Full support 6

Samsung Internet Android

Full support 1.0

readyState Chrome

Full support 43

Edge

Full support 12

Firefox

Full support 19

IE

Full support 10

Opera

Full support 30

Safari

Full support 10

WebView Android

Full support 43

Chrome Android

Full support 43

Firefox Android

Full support 19

Opera Android

Full support 30

Safari iOS

Full support 10

Samsung Internet Android

Full support 4.0

send Chrome

Full support 4

Edge

Full support 12

Firefox Full support 18

Notes'

Full support 18

Notes'

Notes' See bug 775368. No support 11 — 18

Notes'

Notes' Only parameter of type ArrayBuffer and String supported. No support 8 — 11

Notes'

Notes' Only parameter of type String supported. No support 4 — 8

Notes'

Notes' Only parameter of type String supported. Returns boolean.

IE

Full support 10

Opera

Full support 12.1

Safari

Full support 5

WebView Android

Full support ≤37

Chrome Android

Full support 18

Firefox Android Full support 18

Notes'

Full support 18

Notes'

Notes' See bug 775368. No support 14 — 18

Notes'

Notes' Only parameter of type ArrayBuffer and String supported. No support 8 — 14

Notes'

Notes' Only parameter of type String supported. No support 4 — 8

Notes'

Notes' Only parameter of type String supported. Returns boolean.

Opera Android

Full support 12.1

Safari iOS

Full support 4.2

Samsung Internet Android

Full support 1.0

url Chrome

Full support Yes

Edge

Full support 12

Firefox

Full support Yes

IE

?

Opera

Full support Yes

Safari

Full support Yes

WebView Android

Full support Yes

Chrome Android

Full support Yes

Firefox Android

Full support Yes

Opera Android

Full support Yes

Safari iOS

Full support Yes

Samsung Internet Android

Full support Yes

Available in workers Chrome

Full support Yes

Edge

Full support ≤18

Firefox

Full support 37

IE

?

Opera

?

Safari

?

WebView Android

Full support Yes

Chrome Android

Full support Yes

Firefox Android

Full support 37

Opera Android

?

Safari iOS

?

Samsung Internet Android

Full support Yes

Legend

Full support  
Full support
Compatibility unknown  
Compatibility unknown
See implementation notes.'
See implementation notes.
Requires a vendor prefix or different name for use.'
Requires a vendor prefix or different name for use.


See also