How the User-Agent Parser & Browser Inspector Works
The User-Agent Parser & Browser Inspector by DwellixTools analyzes HTTP User-Agent header strings directly inside your web browser. Using pattern-matching regex engines and modern Web APIs (navigator.userAgentData, WebGL debug info, screen metrics), it extracts structural device details with zero server uploads.
Key Features & Inspector Capabilities
- Automatic Browser Detection: Displays your active browser User-Agent string, screen resolution, device pixel ratio (DPR), hardware cores, and WebGL graphics GPU renderer upon loading.
- Custom UA String Parser: Paste any raw User-Agent string from web server logs, mobile apps, or web crawlers to instantly inspect its device breakdown.
- Bot & Crawler Identifier: Detects search engine bots (Googlebot, Bingbot, YandexBot, DuckDuckBot, Baiduspider) and AI scrapers.
- Pre-set UA Library: Quick sample buttons for Chrome Windows, Safari iOS, Android Chrome, Googlebot Desktop, macOS Safari, and Linux Firefox.
- JSON Data Export: Copy structured JSON output containing parsed browser, OS, engine, and hardware metrics for API testing or debugging.
- 100% Client-Side Privacy: Your User-Agent headers and screen metrics are processed entirely inside your local browser window.
Why Inspect User-Agent Strings?
User-Agent headers are sent by web browsers to web servers with every HTTP request. Inspecting UA strings is essential for developers, QA testers, and security engineers:
- Web Development & Cross-Browser Testing: Verify how your application responds to different browser engines (Blink, WebKit, Gecko).
- Mobile Responsive Debugging: Test user-agent conditional logic for mobile phones, tablets, and desktop displays.
- SEO & Bot Analysis: Identify search engine crawlers and verify if incoming traffic originates from legitimate web bots or human visitors.
- Log Inspection: Analyze web server access logs (Nginx, Apache, Cloudflare) to decode user device demographics.
How to Parse User-Agent Strings Step-by-Step
- View Active UA: The top banner automatically displays your active browser User-Agent string and hardware capabilities.
- Paste Custom UA: Paste any HTTP User-Agent string into the text box, or select a sample preset chip.
- Inspect Results: View the instant breakdown of Browser Name, Version, Engine, Operating System, Architecture, and Device Type.
- Copy JSON: Click Copy JSON Output to copy structured data to your clipboard.
Frequently Asked Questions (FAQ)
What is a User-Agent String?
A User-Agent (UA) string is a text header sent by web browsers, mobile apps, and automated bots to web servers. It contains information about the browser version, operating system, rendering engine, and device type.
How do I check what User-Agent string my browser sends?
Simply open this tool — the top banner automatically detects and displays your active User-Agent string along with your screen resolution, DPR, and CPU hardware cores.
Does this tool send my User-Agent string to a database?
No. All string parsing, regex matching, and graphics card rendering checks run 100% locally inside your web browser. No headers or logs are saved on our servers.
How does bot detection work?
The parser checks the User-Agent string against known crawler signatures (such as Googlebot, bingbot, Baiduspider, DuckDuckBot, GPTBot). If a match is found, it labels the device category as a Bot / Crawler.