Browser, OS and device detection based on the available user agent string. Can be used both in a browser (also as a standalone script) or in a server environment.

it's very rarely a good idea to use user agent sniffing. You can almost always find a better, more broadly compatible way to solve your problem! MDN: Browser detection using the user agent

Note: Sniffr is written in Typescript and includes all the necessary typings, can be used both in JavaScript and Typescript projects

Why use it

In case some browser-specific issue cannot be fixed uniformly across browsers we may need to perform some browser detection. For example, browser X crashes when function Y from library Z is used, so we have to detect when we are dealing with browser X and disable library Z.

What is recognized

Browsers

• Firefox
• Internet Explorer
• Edge
• Chrome
• Opera
• Opera mini
• Safari
• Android Browser
• BlackBerry Browser
• Yandex Browser
• SeaMonkey

Operating Systems

• Windows
• Linux
• Mac OS
• ChromeOS
• iOS
• Blackberry OS
• OpenBSD
• Android
• Firefox OS
• Windows Phone
• Windows Mobile

Devices

• iPad
• iPhone
• Galaxy
• HTC
• Nexus
• Nokia
• Lumia
• Blackberry
• XBox

Installation

NPM

To install the library use npm:

npm install sniffr

As a standalone script in a browser

Hosted version (by jsDelivr) can be found here (replace the version number) https://cdn.jsdelivr.net/gh/amoilanen/[email protected]/dist/sniffr.standalone.min.js

https://github.com/amoilanen/sniffr/blob/master/dist/sniffr.standalone.min.js is a downloadable minified version of the library to be used as a standalone script in a browser.

How to use in a browser

NPM

The library can be directly used in a browser, no server-side code is run.

import { RecognizedBrowser } from "sniffr"

//If Windows and Firefox 28 or later
if (RecognizedBrowser.os.name === "windows"
  && RecognizedBrowser.browser.name === "firefox" && RecognizedBrowser.browser.version[0] >= 28) {
  //Apply some workaround
}

Using User-Agent and Client Hints API (Recommended for improved accuracy)

For better accuracy in modern browsers, use the async sniffHints() method which leverages the User-Agent Client Hints API:

import Sniffr from "sniffr"

const sniffr = new Sniffr()
await sniffr.sniffHints()

//If Windows and Firefox 28 or later
if (sniffr.os.name === "windows"
  && sniffr.browser.name === "firefox" && sniffr.browser.version[0] >= 28) {
  //Apply some workaround
}

The sniffHints() method automatically:

• Uses User-Agent Client Hints API when available (Chrome, Edge, Opera, Brave, etc.)
• Gracefully falls back to user agent string parsing for unsupported browsers (Firefox, Safari, etc.)
• Provides more reliable OS, browser, and device detection

For backward compatibility purposes the old sniff method is also supported. This one uses only the user agent string and ignored the Client Hints API:

import Sniffr from "sniffr"

const sniffr = new Sniffr()
sniffr.sniff()

//If Windows and Firefox 28 or later
if (sniffr.os.name === "windows"
  && sniffr.browser.name === "firefox" && sniffr.browser.version[0] >= 28) {
  //Apply some workaround
}

As a standalone script

When the script is loaded Sniffr object will be initialized and put to the global namespace, it can be accessed directly:

//If Windows and Firefox 28 or later
if (Sniffr.os.name === "windows"
  && Sniffr.browser.name === "firefox" && Sniffr.browser.version[0] >= 28) {
  //Apply some workaround
}

API

RecognizedBrowser (module-level exports)

• RecognizedBrowser.os: operating system
• RecognizedBrowser.browser: browser
• RecognizedBrowser.device: device

Sniffr class methods

sniff(userAgentString?: string): this

Synchronous method that detects browser, OS, and device information using user agent string parsing only.

• Usage: Useful for backward compatibility and server-side usage
• Parameters: Optional user agent string. If not provided, uses navigator.userAgent in browser
• Returns: this (Sniffr instance for chaining)
• Supports: All browsers

Example:

const sniffr = new Sniffr()
sniffr.sniff()
console.log(sniffr.browser.name)

sniffHints(userAgentString?: string): Promise<this>

Asynchronous method that uses User-Agent Client Hints API when available for more accurate detection, with automatic fallback to user agent string parsing.

• Usage: Recommended for browser environments where accuracy is important
• Parameters: Optional user agent string. If not provided, attempts to fetch UA hints from the browser
• Returns: Promise<this> (resolves to Sniffr instance)
• Supports: All browsers (with graceful fallback for unsupported ones)
• Privacy: When UA hints are unavailable or rejected by the browser, falls back to user agent string
• Availability: Automatically detects User-Agent Client Hints API support; no browser checks needed

Example:

const sniffr = new Sniffr()
await sniffr.sniffHints()
console.log(sniffr.browser.name)

How to use on the server side

Sniffr can also be used in a Node.js environment in case you need to do some server-side user agent analysis as well.

First install it

npm install sniffr

Then load the module, provide it the agent string and query the results just like in a browser environment:

var Sniffr = require("sniffr").default;
var s = new Sniffr();

s.sniff("Mozilla/5.0 (iPad; CPU OS 6_0 like Mac OS X) AppleWebKit/536.26 (KHTML, like Gecko) Version/6.0 Mobile/10A5355d Safari/8536.25");

console.log("Operating System:");
console.log(s.os);
console.log("Browser:");
console.log(s.browser);
console.log("Device:");
console.log(s.device);

Other libraries

Some libraries like jQuery provide only browser information and not the OS information. Some like Detectizr are plugins for other libraries that you may not use. And some require server-side code. A few libraries are usable only on the server or only in a browser.

Sniffr provides simple and symmetric API, does not depend on other libraries, does not require the server part, is tiny, fast and easily extensible. In addition, it can be used both in browser and server environments.

Credits

The original sniffing dog image location is http://publicdomainvectors.org/en/free-clipart/Dog-sniffing-vector-image/11807.html