Web/API/WebSockets API-2 < Web/API

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

• Writing WebSocket client applications
• Writing WebSocket servers
• Writing a WebSocket server in C#
• Writing a WebSocket server in Java

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

• AJAX
• JavaScript

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

The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.

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

• RFC 6455 — The WebSocket Protocol
• WebSocket API Specification
• Server-Sent Events

The WebSocket API (WebSockets) by Mozilla Contributors is licensed under CC-BY-SA 2.5.