A Browser detector. Because sometimes, there is no other way, and not even good modern browsers always provide good feature detection mechanisms.



A Browser detector. Because sometimes, there is no other way, and not even good modern browsers always provide good feature detection mechanisms.

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The library is made to help to detect what browser your user has and gives you a convenient API to filter the users somehow depending on their browsers.

Please, note that this is an alpha version. Check out the 1.x branch for a stable version.

Changes of the 2.0 The upcoming 2.0 version has drastically changed API. All available methods can be found in the docs folder from now on and on a webpage soon.

Use cases

First of all, require the library:

const bowser = require('bowser');

By default, require('bowser') requires the ES5 version of files, which do not include any polyfills.

In case if you don't use your own babel-polyfill you may need to have pre-built bundle with all needed polyfills. So, for you it's suitable to require bowser like this: require('bowser/bundled'). As the result, you get a ES5 version of bowser with babel-polyfill bundled together.

You may need to use the source files, so they will be available in the package as well.

Browser props detection

Often we need to pick users' browser properties such as the name, the version, the rendering engine and so on. Here is an example how to make it with Bowser:

const browser = bowser.getParser(window.navigator.userAgent);

console.log(`The current browser name is "${browser.getBrowserName()}"`);
// The current browser name is "Internet Explorer"


const impression = new Impression();

const browser = bowser.getParser(window.navigator.userAgent);
const browserInfo = browser.getBrowser();
impression.brName =;
impression.brVer = browserInfo.version;


const browser = bowser.getParser(window.navigator.userAgent);
impression.userTechData = browser.parse();
// outputs
  browser: {
    name: "Internet Explorer"
    version: "11.0"
  os: {
    name: "Windows"
    version: "NT 6.3"
    versionName: "8.1"
  platform: {
    type: "desktop"
  engine: {
    name: "Trident"
    version: "7.0"

Filtering browsers

You could want to filter some particular browsers to provide any special support for them or make any workarounds. It could look like this:

const browser = bowser.getParser(window.navigator.userAgent);
const isValidBrowser = browser.satisfies({
  // declare browsers per OS
  windows: {
    "internet explorer": ">10",
  macos: {
    safari: ">10.1"

  // per platform (mobile, desktop or tablet)
  mobile: {
    safari: '>9',
    'android browser': '>3.10'

  // or in general
  chrome: ">20.1.1432",
  firefox: ">31",
  opera: ">22"
  // also supports equality operator
  chrome: "=20.1.1432", // will match particular build only

  // and loose-equality operator
  chrome: "~20"         // will match any 20.* sub-version
  chrome: "~20.1"       // will match any 20.1.* sub-version (20.1.19 as well as

Settings for any particular OS or platform has more priority and redefines settings of standalone browsers. Thus, you can define OS or platform specific rules and they will have more priority in the end.

More of API and possibilities you will find in the docs folder.


If you'd like to contribute a change to bowser, modify the files in src/, then run the following (you'll need node + npm installed):

$ npm install
$ npm test

Adding tests

See the list in test/acceptance/useragentstrings.yml with example user agents and their expected bowser object.

Whenever you add support for new browsers or notice a bug / mismatch, please update the list and check if all tests are still passing.

Similar Projects

  • Kong - A C# port of Bowser.


Licensed as MIT. All rights not explicitly granted in the MIT license are reserved. See the included LICENSE file for more details.