User-Agent Parser

Paste a browser or device user-agent string below to parse and analyze it. Instantly see browser, OS, device, and more for debugging and development.

User Agent Analysis

Every browser sends a "user agent" string identifying itself. These strings are notoriously complex - a typical one might claim to be Chrome, Safari, AND Firefox simultaneously for compatibility reasons.

This tool parses user agents and extracts the actual browser, version, operating system, and device type. Useful for analytics, debugging, or understanding what browsers are visiting your site.

What Gets Detected

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

Understanding User-Agent Strings

User-Agent strings are HTTP headers that browsers send to identify themselves to web servers. A typical string includes the browser name and version, rendering engine, operating system, and platform. Example: "Mozilla/5.0 (Windows NT 10.0; Win64; x64) Chrome/91.0.4472.124" indicates Chrome 91 on Windows 10 64-bit.

The "Mozilla/5.0" prefix is a historical artifact from browser wars when sites blocked non-Netscape browsers. Today, almost all browsers include it for compatibility. User-Agent strings have become complex and often misleading'modern best practice is feature detection rather than browser detection.

Frequently Asked Questions

Why do all browsers say "Mozilla"?

Historical compatibility. In the 1990s, servers would send better content to "Mozilla" (Netscape) browsers. When IE and others wanted this content, they added "Mozilla" to their user-agent. Now everyone includes it, making that prefix meaningless.

Can user-agents be faked?

Yes, easily. Browser extensions, developer tools, and programming can change user-agent strings. Never rely on user-agent for security or critical functionality. Use feature detection (checking if a capability exists) instead of browser detection.

What is Client Hints?

Client Hints are a modern replacement for user-agent strings. Instead of one messy string, the browser sends structured headers like Sec-CH-UA-Platform for OS and Sec-CH-UA for browser. This provides cleaner, more reliable detection while reducing fingerprinting surface.

How do I detect bots vs real browsers?

Bots often have distinctive user-agents containing "bot," "crawler," or "spider." Googlebot, Bingbot, and others self-identify. However, malicious bots may spoof legitimate browser user-agents. For reliable bot detection, combine user-agent analysis with behavioral patterns and CAPTCHA systems.

Why are user-agent strings so long and complex?

Historical baggage. Each new browser added tokens to claim compatibility with predecessors. Chrome claims to be "like Gecko" (Firefox's engine) and "Safari" compatible. The result is bloated strings with redundant information. This is why Client Hints are being developed as a cleaner alternative.