What is a User-Agent string?
The User-Agent HTTP header tells servers which client made a request—a desktop browser, mobile app, API client, or search crawler. Analytics pipelines, WAF rules, and responsive design often read it from access logs.
User Agent Parser
Decode UA strings. Identify browser, OS, device, and bots
Use this free user agent parser to decode any HTTP User-Agent string instantly. Identify browser, engine, operating system, device type, and bot/crawler status. Perfect for debugging analytics, log analysis, and compatibility checks. Single and bulk modes. 100% client-side — your data never leaves your browser.
From the blog
Lease Pattern in Distributed Systems Explained
Read
How time-bound leases give cluster nodes exclusive access without holding it forever when things go wrong
Mode:
Parsing runs as you type. Click My Browser to inspect your current session.
One UA per line. Up to 5,000 lines. Processed locally in your browser.
Common User-Agent Tokens
Browser & Engine Tokens
Mozilla/5.0 | Compatibility prefix (historical) |
AppleWebKit | WebKit-based rendering engine |
Gecko | Firefox engine family |
Chrome/ | Chromium version (also Edge, Opera) |
Safari/ | Safari or WebKit version token |
Edg/ | Microsoft Edge (Chromium) |
Platform & Bot Indicators
Windows NT | Windows desktop |
iPhone / iPad | Apple mobile / tablet |
Android | Android OS |
Mobile | Mobile-optimized browser |
bot / crawl | Likely crawler or spider |
curl / wget | Command-line HTTP client |
User-Agent Guide
Structure of a typical browser UA
- Product token: Usually
Mozilla/5.0for compatibility with legacy server sniffing. - Platform: OS details such as
Windows NT 10.0,Macintosh, oriPhone; CPU iPhone OS 17_2. - Engine:
AppleWebKit/537.36orGecko/20100101identifies the rendering engine. - Browser: The actual product, e.g.
Chrome/120.0.0.0orFirefox/121.0, often after a Safari compatibility token.
User-Agent Client Hints
Modern Chromium browsers also send Client Hints headers (Sec-CH-UA, Sec-CH-UA-Mobile, Sec-CH-UA-Platform) with structured, less spoofable metadata. The classic User-Agent string is still widely logged; this tool parses that header. For Client Hints, inspect request headers in your browser Network tab.
Using this user agent parser
- Single mode: Paste one UA from nginx, Apache, CloudFront, or browser devtools.
- My Browser: Instantly decode
navigator.userAgentfrom your session. - Bulk mode: Paste log extracts (one line per UA) and export CSV for spreadsheets.
- Bot detection: Review the Bot column before filtering crawlers from traffic reports.
- Privacy: All parsing happens locally—safe for production log samples.
User Agent Parser FAQ
What is a User-Agent string?
A User-Agent string is sent in the User-Agent HTTP header. It describes the client—browser, app, or bot—making the request. Servers log it for analytics, compatibility, and bot filtering.
What does a typical User-Agent look like?
Most browsers start with Mozilla/5.0, then platform tokens, engine details (AppleWebKit or Gecko), and end with the real browser name like Chrome/120.0.0.0.
How do I detect bots and crawlers?
Look for bot, crawl, spider, or names like Googlebot. CLI tools send curl, python-requests, or similar. This parser flags likely bots automatically.
How do I tell mobile from desktop?
Mobile UAs include Mobile, Android, or iPhone. Tablets often list iPad. The device class badge shows desktop, mobile, tablet, or bot.
What are User-Agent Client Hints?
Client Hints (Sec-CH-UA-*) are newer headers with structured browser/platform data. They complement the User-Agent string. This tool parses the classic User-Agent header.
Can User-Agent strings be spoofed?
Yes. Any client can send a fake UA. Use it for analytics and coarse hints—not as a security boundary. Combine with Client Hints, CAPTCHAs, or rate limiting for bots.
Is it safe to parse user agents online?
This tool runs 100% in your browser. UA strings are never uploaded. Your log data stays on your machine unless you export it.
How does this compare to CLI UA parsers?
Python ua-parser, npm packages, and log processors offer similar output for scripts. This browser tool is ideal for quick checks, sharing with teammates, and bulk paste without installing tools.