User Agent Parser

What is a User-Agent String?

A User-Agent (UA) string is a text header that browsers and bots send with every HTTP request to identify themselves. It reveals the browser name, version, operating system, device model, and more. Our parser uses the industry-standard ua-parser-js library to extract structured information from any UA string.

Why AI Cannot Parse User-Agent Strings

AI models hallucinate UA parsing results because they rely on training patterns rather than deterministic regex rules. UA strings have no formal grammar — every browser invented its own format over 30+ years. AI often confuses Chromium-based browsers (Chrome, Edge, Brave, Opera), misidentifies iOS Safari vs macOS Safari, and cannot detect new browser versions or AI crawlers that appeared after its training cutoff. Our tool uses ua-parser-js v2.0.10 with regularly updated browser and bot pattern databases for 100% deterministic results.

How to Use

1. Paste a User-Agent string into the text area, or click a sample button to load a test UA
2. Click "Use My UA" to auto-fill your current browser's user agent
3. Click "Parse" to extract browser, OS, device, and bot information
4. Copy the results as JSON for use in tickets, logs, or scripts

FAQs

What does the parser detect?

Browser name and version, rendering engine (Blink, WebKit, Gecko), operating system and version, device vendor/model/type (mobile, tablet, desktop, TV, console), CPU architecture, and bot/crawler identity including AI crawlers like GPTBot, ClaudeBot, PerplexityBot, and Google-Extended.

Is my UA string sent to any server?

No. All parsing happens entirely in your browser using the ua-parser-js library. Your UA string never leaves your device. You can disconnect from the internet after the page loads and the tool still works.

What bots and crawlers are detected?

Search bots (Googlebot, Bingbot, Yandex, Baidu, DuckDuckBot), AI crawlers (GPTBot, ChatGPT-User, ClaudeBot, PerplexityBot, CCBot, Google-Extended, Bytespider), SEO tools (AhrefsBot, SemrushBot, Majestic), social preview fetchers (Facebook, Twitter, LinkedIn, Slack, Discord, Telegram), and automation frameworks (HeadlessChrome, Puppeteer, Playwright).

What library does this use?

We use ua-parser-js v2.0.10, the most comprehensive and up-to-date JavaScript UA parsing library with 10,000+ GitHub stars and 28M+ weekly npm downloads. It supports Client Hints and has pattern databases updated for 2026 browser and crawler releases.

Why does my browser show the wrong OS?

UA strings can be frozen or reduced by privacy initiatives. Chrome's User-Agent Reduction (2022-2024) freezes minor version numbers to "0" and strips device model info. For the most accurate results, modern browsers support User-Agent Client Hints (Sec-CH-UA-*) which provide structured, opt-in headers.

Can I use this for log analysis?

Yes. Paste UA strings from server logs, CDN access logs, or analytics to identify browser distribution, bot traffic, and device types. Each paste gives you structured JSON output ready to copy into tickets or analysis tools.

Is there a bulk mode?

This tool parses one UA string at a time for detailed inspection. For bulk analysis, use the ua-parser-js library directly in your data pipeline. The library is available on npm and works in Node.js environments.

Common Use Cases

• Debugging: A user reports a bug — ask them for their UA string and parse it here to know their exact browser and OS
• Log Forensics: Inspect suspicious UA strings from server logs to identify bots, crawlers, or automated tools
• Analytics Validation: Verify that your analytics correctly identifies browser versions and device types
• AI Crawler Audit: Identify AI training crawlers in your logs to adjust robots.txt policies
• Support Tickets: Copy structured browser/OS/device info into support tickets for faster resolution