Utilities2026-06-262 min read

Online User-Agent Parser: Identify Browser and Device Information

What Is User-Agent Parsing

User-Agent parsing converts the browser's User-Agent string into structured information (browser, version, operating system, device type, etc.).

User-Agent String Structure

Mozilla/5.0 (iPhone; CPU iPhone OS 16_0 like Mac OS X)
AppleWebKit/605.1.15 (KHTML, like Gecko)
Version/16.0 Mobile/15E148 Safari/604.1
│           │                    │        │
│           │                    │        └─ Browser version
│           │                    └─ Browser name
│           └─ Operating system
└─ Engine version

Parsed Result Example

{
  "browser": {
    "name": "Safari",
    "version": "16.0",
    "engine": "WebKit",
    "engineVersion": "605.1.15"
  },
  "os": {
    "name": "iOS",
    "version": "16.0",
    "platform": "iPhone"
  },
  "device": {
    "type": "mobile",
    "brand": "Apple",
    "model": "iPhone"
  },
  "isMobile": true,
  "isTablet": false,
  "isDesktop": false
}

Why You Need User-Agent Parsing

Data analytics: Track user browser and device distribution
Compatibility testing: Identify old browsers and provide fallbacks
Responsive design: Adjust interface based on device type
Security analysis: Detect spoofed or unusual User-Agents
SEO optimization: Provide optimized content per device
Ad targeting: Serve device-specific advertisements

How to Use an Online Tool

Using ToolVault's User-Agent Parser:

Paste the complete User-Agent string
Auto-parse into structured JSON
View browser, OS, device details
Flag mobile/desktop/tablet
One-click copy parsed result

Parsing in Code

JavaScript

function parseUserAgent(ua) {
  const result = {
    browser: { name: 'Unknown', version: '' },
    os: { name: 'Unknown', version: '' },
    device: { type: 'desktop' },
  };

  // Detect OS
  if (/iPhone|iPad|iPod/.test(ua)) {
    result.os.name = 'iOS';
    result.os.platform = /iPhone/.test(ua) ? 'iPhone' : 'iPad';
    result.device.type = /iPad/.test(ua) ? 'tablet' : 'mobile';
  } else if (/Windows/.test(ua)) {
    result.os.name = 'Windows';
    const match = ua.match(/Windows NT (\d+\.\d+)/);
    if (match) result.os.version = match[1];
  } else if (/Mac OS X/.test(ua)) {
    result.os.name = 'macOS';
    const match = ua.match(/Mac OS X (\d+[._]\d+)/);
    if (match) result.os.version = match[1].replace('_', '.');
  } else if (/Android/.test(ua)) {
    result.os.name = 'Android';
    result.device.type = /Mobile/.test(ua) ? 'mobile' : 'tablet';
  }

  // Detect browser
  if (/Chrome/.test(ua) && !/Edg/.test(ua)) {
    result.browser.name = 'Chrome';
    const match = ua.match(/Chrome\/(\d+\.\d+)/);
    if (match) result.browser.version = match[1];
  } else if (/Safari/.test(ua) && !/Chrome/.test(ua)) {
    result.browser.name = 'Safari';
  } else if (/Firefox/.test(ua)) {
    result.browser.name = 'Firefox';
  } else if (/Edg/.test(ua)) {
    result.browser.name = 'Edge';
  }

  return result;
}

Python

import re

def parse_user_agent(ua):
    result = {
        'browser': {'name': 'Unknown', 'version': ''},
        'os': {'name': 'Unknown', 'version': ''},
        'device': {'type': 'desktop'}
    }

    if 'iPhone' in ua or 'iPad' in ua:
        result['os']['name'] = 'iOS'
        result['device']['type'] = 'mobile' if 'iPhone' in ua else 'tablet'
    elif 'Windows' in ua:
        result['os']['name'] = 'Windows'
    elif 'Mac OS X' in ua:
        result['os']['name'] = 'macOS'
    elif 'Android' in ua:
        result['os']['name'] = 'Android'
        result['device']['type'] = 'mobile' if 'Mobile' in ua else 'tablet'

    if 'Chrome' in ua and 'Edg' not in ua:
        result['browser']['name'] = 'Chrome'
    elif 'Safari' in ua and 'Chrome' not in ua:
        result['browser']['name'] = 'Safari'
    elif 'Firefox' in ua:
        result['browser']['name'] = 'Firefox'

    return result

FAQ

Will User-Agent Strings Be Deprecated?

Yes, Google Chrome is rolling out User-Agent Reduction. Future versions will send simplified UA info. Consider using the Client Hints API as a replacement.

How to Detect Bots and Crawlers?

Check for bot, crawler, spider keywords in UA. But note: malicious crawlers can spoof UA, so combine with other signals like request frequency, behavior patterns, and parsing URL parameters for full request context.

How to Distinguish Mobile vs Desktop?

Primary signals: 1) UA contains Mobile/Android/iPhone; 2) Screen resolution (< 768px typically mobile); 3) Touch support (ontouchstart).

This article is brought to you by ToolVault. More developer tools at the homepage.

Password Generator - Online Secure Password GeneratorUtilities

Timestamp Converter - Unix Timestamp Online ConverterUtilities

CIDR Calculator - IPv4 Subnet CalculatorUtilities

← Back to Blog