Client Installation

[1] Yes, with

Please check the associated migration guides:

v3 to v4

Socket.IO does support IE9 and above. IE 6/7/8 are not supported anymore.

Browser compatibility is tested thanks to the awesome Sauce Labs platform:

The release notes of each version can be found in .

will be registered as a global variable:

If you don’t need this (see other options below), you can disable the functionality on the server side:

You can also include the client bundle from a CDN:

Socket.IO is also available from other CDN:

cdnjs: https://cdnjs.cloudflare.com/ajax/libs/socket.io/4.1.2/socket.io.min.js
jsDelivr:

There are several bundles available:

Name	Size	Description
socket.io.js	34.7 kB gzip	Unminified version, with debug
socket.io.min.js	14.7 kB min+gzip	Production version, without
socket.io.msgpack.min.js	15.3 kB min+gzip	Production version, without debug and with the

The debug package allows to print debug information to the console. You can find more information .

For production, please use the socket.io.min.js bundle, which is an optimized build excluding the debug package.

The Socket.IO client is compatible with bundlers like webpack or .

The client can also be run from Node.js.

Note: for the reasons cited above, you may want to exclude debug from your browser bundle. With webpack, you can use webpack-remove-debug.

Note for TypeScript users: the types are now included in the package and thus the types from @types/socket.io-client are not needed anymore and may in fact cause errors:

Caught a mistake? Edit this page on