Online User-Agent Parser: Identify Browser and Device Information

utility2026-07-252 min read

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 DevToolkit Pro'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. Combine with other signals (request frequency, behavior patterns).

How to Distinguish Mobile vs Desktop?

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

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