Please make sure that Node.js is installed on your system. The current Long Term Support (LTS) release is an ideal starting point.

At least Node.js 8 is needed, older versions are not supported anymore.


The latest Socket.IO release is:

NPM version

To install the latest release:

$ npm install

To install a specific version:

$ npm install<version>

Additional packages

By default, Socket.IO use the WebSocket server provided by the ws package.

There are 2 optional packages that can be installed alongside this package. These packages are binary add-ons which improve certain operations. Prebuilt binaries are available for the most popular platforms so you don’t necessarily need to have a C++ compiler installed on your machine.

  • bufferutil: Allows to efficiently perform operations such as masking and unmasking the data payload of the WebSocket frames.
  • utf-8-validate: Allows to efficiently check if a message contains valid UTF-8 as required by the spec.

To install those packages:

$ npm install --save-optional bufferutil utf-8-validate

Please note that these packages are optional, the WebSocket server will fallback to the Javascript implementation if they are not available. More information can be found here.

Other WebSocket server implementations

Any Websocket server implementation which exposes the same API as ws (notably the handleUpgrade method) can be used.

For example, you can use the eiows package, which is a fork of the (now deprecated) uws package:

$ npm install eiows

And then use the wsEngine option:

const io = require('')(3000, {
wsEngine: 'eiows'

This implementation “allows, but doesn’t guarantee” significant performance and memory-usage improvements over the default implementation. As usual, please benchmark it against your own usage.

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