User Agent Parser & Decoder
Analyze and decode any user agent string to detect browser, operating system, device type, and bots. Free, fast, and 100% client-side. No data stored.
What is a User Agent String?
A user agent string is an HTTP header sent by your web browser every time it makes a request to a server.
It contains information about your browser name, version, operating system, device type, and rendering engine.
Example of a real user agent string:
Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36
This string tells a server: “I’m a Chrome browser on Windows 10, 64-bit architecture, with WebKit engine.”
Servers use this information to optimize content delivery, detect mobile vs desktop, identify bots, and debug compatibility issues.
Why Parse User Agent Strings?
🔍 Browser Detection
Identify which browsers are accessing your site (Chrome, Safari, Firefox, Edge, etc.) and their versions.
📱 Device Detection
Determine if users are on desktop, mobile, or tablet. Serve device-specific experiences.
🤖 Bot Detection
Identify search engine crawlers (Googlebot, Bingbot), social bots, and security analysis tools.
🐛 Debugging
Troubleshoot compatibility issues by understanding what browsers are having problems.
📊 Analytics
Analyze your traffic sources: which OS versions are most common, browser market share, etc.
🔐 Security
Detect suspicious user agents, identify scrapers, and protect against automated attacks.
How User Agent Parsing Works
User agent strings follow loose patterns. Different browsers format them differently, making parsing complex. Here's what parsers look for:
- Browser identification: Look for keywords like "Chrome", "Safari", "Firefox", "Edge"
- Version extraction: Find version numbers (e.g., "120.0.0.0")
- OS detection: Identify Windows, macOS, Linux, iOS, Android from specific markers
- Device type: Keywords like "Mobile", "Tablet", "iPad" indicate device class
- Bot detection: Look for bot signatures (Googlebot, bot, crawler, spider)
- Engine identification: Detect rendering engines (WebKit, Gecko, Trident, Blink)
User Agent Parser Tools Comparison
Compare popular user agent parsing tools and their features:
| Tool |
Type |
Best For |
Key Features |
Pricing |
| WhatIsMyBrowser |
Commercial |
Enterprise API users, large-scale analysis |
Huge UA database, API access, accuracy tracking, historical data |
Freemium + API pricing |
| BrowserScan |
Free |
General parsing, browser info |
Clean UI, quick parsing, multiple utility tools |
Free |
| Google Admin Toolbox |
Free |
Google Workspace teams, basic parsing |
Part of Google toolchain, simple interface |
Free (Google-backed) |
| IT-Tools |
Open Source |
Developers, self-hosted parsing |
100+ dev tools bundled, fast, minimal design |
Free (open source) |
| UAParser (Library) |
Open Source |
Backend developers, JavaScript/Node.js |
npm library, integrates into code, regex-based |
Free (npm) |
| 51Degrees |
Commercial |
Enterprise detection, real-time data |
Real-time UA database updates, high accuracy, APIs |
Enterprise pricing |
How to Choose the Right User Agent Parser
For Individual Developers & Learning
Use BrowserScan or this tool. Free, no registration, instant results.
Great for quick debugging and understanding user agents.
For Small Teams & Websites
Use Google Admin Toolbox (if you're already in Google Workspace ecosystem) or
IT-Tools (self-hosted). Simple, reliable, free.
For Backend Development
Use UAParser library (JavaScript/Node.js) or similar language-specific libraries.
Integrate parsing directly into your application code.
For Enterprise & Analytics
Use WhatIsMyBrowser API or 51Degrees. They maintain massive UA databases,
offer real-time updates, and handle edge cases. Worth the cost for high-volume operations.
For Privacy-First Organizations
Self-host IT-Tools or use open-source UAParser libraries.
Data never leaves your servers. Full control over accuracy and updates.
Common User Agent String Patterns
Chrome on Windows
Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36
Note: Chrome always includes “Safari” in its UA for WebKit compatibility
Safari on iPhone
Mozilla/5.0 (iPhone; CPU iPhone OS 17_3 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/17.3 Mobile/15E148 Safari/604.1
Look for: iPhone OS version, Mobile keyword
Googlebot (Search Engine)
Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)
Search engines identify themselves explicitly
Chrome on Android
Mozilla/5.0 (Linux; Android 13; SM-G991B) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Mobile Safari/537.36
Android, Linux, and “Mobile” keyword present
Frequently Asked Questions
What is a user agent string?
A user agent string is an HTTP header sent by your browser to web servers.
It identifies your browser name, version, operating system, device type, and other system information.
Why would I need to decode a user agent?
Developers decode user agents to detect browsers, identify bots/crawlers, detect devices, troubleshoot compatibility issues,
analyze traffic sources, and implement device-specific features.
Can this detect bots and crawlers?
Yes. Search engine bots (Googlebot, Bingbot), social media crawlers (Facebook, Twitter), and security tools
include identifiable signatures in their user agent strings.
Is this tool secure? Does it store my data?
Completely secure. This tool runs 100% client-side in your browser. No data is sent to any server. Nothing is logged or stored.
Can I detect mobile vs desktop from user agent?
Yes. User agent strings contain keywords like 'Mobile', 'Tablet', 'iPad', 'Android' that indicate device type.
Modern tools analyze these patterns for accurate detection.
What's the difference between parsing and decoding?
Parsing extracts structured data from a user agent string. Decoding interprets what those extracted values mean
(e.g., parsing gets 'Chrome/120', decoding tells you 'Google Chrome version 120').
How accurate is user agent detection?
Very accurate for browsers and OS. Users can spoof user agents or browsers can change format without warning.
Enterprise tools like 51Degrees maintain massive databases to handle edge cases and keep accuracy high.
Are user agents being phased out?
User agents won't disappear but are becoming less detailed. Google's "User-Agent Client Hints" (UA-CH) aims to replace them.
But UA strings will remain useful for years. Both technologies will coexist during transition period.
Getting Started with User Agent Parsing
If you're developing a website or application, here's how to integrate user agent parsing:
For Web Developers (JavaScript)
- Install UAParser.js:
npm install ua-parser-js
- Import and use:
const parser = new UAParser(); const result = parser.getResult();
- Access parsed data: browser name, OS, device type, engine version
- Implement conditional logic based on browser/device
For Backend Developers (Node.js/Python)
- Use language-specific UA parser library
- Parse user agent on server:
req.get('User-Agent')
- Log or analyze results for analytics
- Respond with optimized content if needed
💡 Pro Tip: Don't rely solely on user agents for critical decisions.
Combine user agent detection with feature detection (can the browser support WebGL?, etc.)
and runtime testing for most robust results.