cartercole/fingerprintjs

Fast browser fingerprint

fingerprintJS

Fast browser fingerprint library. Written in pure JavaScript, no dependencies. By default uses Murmur hashing and returns a 32bit integer number. Hashing function can be easily replaced. Feather weight: only 843 bytes when gzipped.

What is fingerprinting?

Fingerprinting is a technique, outlined in the research by Electronic Frontier Foundation, of anonymously identifying a web browser with accuracy of up to 94%.

Browser is queried its agent string, screen resolution and color depth, installed plugins with supported mime types, timezone offset and other capabilities, such as local storage and session storage. Then these values are passed through a hashing function to produce a fingerprint that gives weak guarantees of uniqueness.

No cookies are stored to identify a browser.

It's worth noting that a mobile share of browsers is much more uniform, so fingerprinting should be used only as a supplementary identifying mechanism there.

Installation

If you're on Rails, add this to your Gemfile gem 'fingerprintjs-rails' and

bundle install

After that you can add the file to sprockets:

//= require fingerprint

Otherwise, just copy the file to your js directory.

Usage

var fingerprint = new Fingerprint().get();

Using custom hashing function

var hasher = new function(value, seed){ return value.length % seed; }
var fingerprint = new Fingerprint(hasher).get();

Licence

This code is MIT licenced:

Copyright (c) 2013 Valentin Vasilyev

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.