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User Agent Parser

Parse and analyze HTTP user agent strings to identify browser, operating system, device type, and version information for analytics and debugging.

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Parse User Agent Strings

Decode user agent strings to identify browser, OS, device type, and bot status.

Information Extracted

  • Browser name and version
  • Operating system and version
  • Device type (desktop, mobile, tablet)
  • Bot/crawler identification
  • Rendering engine

Uses

Analytics debugging, bot detection, device-specific testing.

Detecting Bots and Crawlers

Identifying Bots in User Agent Strings

Understanding bot traffic is essential for security, analytics, and resource management. Here's how to identify different types of automated traffic.

Legitimate Bot User Agents

Search engine crawlers identify themselves clearly:

BotUser Agent ContainsPurpose
GooglebotGooglebotGoogle search indexing
BingbotbingbotBing search indexing
SlurpSlurpYahoo search indexing
DuckDuckBotDuckDuckBotDuckDuckGo indexing
facebookexternalhitfacebookexternalhitFacebook link previews
TwitterbotTwitterbotTwitter card generation

Suspicious Bot Patterns

Watch for these red flags:

  • Empty or missing user agents
  • Generic library defaults like python-requests/2.x or curl/7.x
  • Outdated browser versions (Chrome 50 when current is 120+)
  • Impossible combinations (Windows + Safari, iPhone + Windows)
  • Known scraper signatures like Scrapy, HTTrack, wget

Bot Detection Strategies

  1. User agent validation - Check for known bot signatures
  2. Behavior analysis - Bots often request pages faster than humans
  3. JavaScript challenges - Many bots can't execute JavaScript
  4. IP reputation - Check against threat intelligence feeds
  5. Request patterns - Bots access URLs in predictable sequences

Blocking Unwanted Bots

# nginx example
if ($http_user_agent ~* (scrapy|wget|curl|python)) {
    return 403;
}

Note: User agents can be spoofed. Use multiple signals for reliable bot detection.

References & Citations

  1. MDN Web Docs. (2024). User-Agent String. Retrieved from https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/User-Agent (accessed January 2025)
  2. web.dev. (2022). User-Agent Client Hints. Retrieved from https://web.dev/user-agent-client-hints/ (accessed January 2025)

Note: These citations are provided for informational and educational purposes. Always verify information with the original sources and consult with qualified professionals for specific advice related to your situation.

Key Security Terms

Understand the essential concepts behind this tool

Browser Fingerprinting

A technique to identify and track users based on unique browser and device characteristics without using cookies.

Learn more →
View all terms in our glossary →

Frequently Asked Questions

Common questions about the User Agent Parser

User agent (UA) string is HTTP header sent by browsers/apps identifying themselves to servers. Format: "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 Chrome/120.0.0.0". Contains: browser name and version (Chrome 120), rendering engine (AppleWebKit, Gecko, Trident), operating system (Windows 10, macOS, iOS, Android), device type (desktop, mobile, tablet), sometimes: language, architecture (64-bit), brand (Samsung, Apple). Used for: analytics, feature detection, mobile optimization, bot detection, browser support warnings. Note: UA strings can be spoofed - not fully reliable for security. This tool parses UA strings into structured, readable information.

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