Browser and User-Agent Inspector
Inspect current browser telemetry or parse custom User-Agent strings to identify browsers, rendering engines, operating systems, hardware concurrency, and search bots.
About Browser and User-Agent Inspector
Web browsers send a User-Agent header with every HTTP request to identify their browser software, rendering engine, operating system, and device architecture. Understanding what your browser discloses is essential for debugging responsive design, testing bot crawlers, and auditing client privacy.
This inspector parses your active navigator string and extracts clean details: your detected browser family, operating system, viewport screen dimensions, device pixel ratio, primary language, and available CPU hardware concurrency.
By evaluating client headers on device, you can see exactly what tracking parameters and hardware footprints your browser exposes to visited websites.
To analyze web client fingerprints, inspect network endpoints with the IP address lookup and check response headers via the HTTP headers inspector.
Step-by-step practical guide
- Open the page to see your raw User-Agent string immediately displayed in the top card.
- Review the detected system cards below for browser family, operating system, and hardware concurrency.
- Click Copy next to your user agent string to capture it for bug reports, support tickets, or development testing.
- Inspect screen pixel density to check High-DPI and Retina display rendering modes.
- Compare detected values when switching between desktop and mobile emulation in developer tools.
Engineering specifications and execution details
Reads data directly from standard window.navigator and window.screen APIs without network transmission.
Extracts screen resolution and window.devicePixelRatio to show both physical and CSS pixel dimensions.
Hardware concurrency reports the number of logical processor threads available to web workers.
Extracts browser engine details (Blink, Gecko, WebKit) using deterministic token parsing.
Runs synchronously with zero overhead and zero external dependencies.
Data privacy and memory isolation
All system diagnostics execute in local browser memory without third-party tracking scripts or logging.
Hardware concurrency and screen dimensions are displayed strictly for user inspection and never logged.
Common production use cases
- Web developers testing in-browser browser feature detection and legacy compatibility.
- QA testers documenting exact browser and OS versions when submitting reproducible bug reports.
- Privacy-conscious users auditing what device information is broadcast to websites.
- Engineers configuring responsive media queries based on screen pixel ratios.
- Support specialists diagnosing customer display and layout rendering issues.
Edge cases and operational boundaries
- User-Agent Client Hints: Modern Chromium browsers are freezing raw User-Agent strings and migrating toward User-Agent Client Hints (sec-ch-ua) to reduce browser fingerprinting.
- Browser masking: Privacy browsers (like Brave or Firefox with anti-fingerprinting enabled) may report generalized OS or resolution values to prevent tracking.
- Mobile emulation: Toggling mobile emulation in Chrome DevTools changes the User-Agent string and screen metrics to simulate mobile hardware.
- Embedded webviews: In-app browsers (like Instagram or LinkedIn webviews) append custom application tokens to standard mobile User-Agent strings.
Frequently Asked Questions
What is a User-Agent string?
A User-Agent is a text string sent by your browser that tells web servers information about your browser name, rendering engine, and operating system.
Why do modern browser user agents contain "Mozilla" and "Safari"?
Historical browser compatibility wars led new browsers to include legacy names in their user agent strings so older web servers would not block them from receiving modern web pages.
What is hardware concurrency?
Hardware concurrency is the number of logical CPU cores available on your device, which browsers expose to allocate multithreaded Web Workers efficiently.
Can websites identify my exact computer using this data?
While a user agent alone does not identify you, combining it with screen resolution and fonts can form a browser fingerprint. Modern browsers are reducing this exposure.
What is devicePixelRatio?
Device pixel ratio is the ratio between physical display pixels and CSS logical pixels. High-DPI screens typically report a ratio of 2 or 3.
Why are browsers freezing User-Agent strings?
Major browser vendors are standardizing on generic User-Agent strings to curb cross-site fingerprinting and protect user privacy across the web.
Can I change my User-Agent string?
Yes. Most modern browsers allow overriding the User-Agent header via developer tools or browser extensions for testing purposes.
How does the parser identify search engine crawlers and generative AI bots like GPTBot or ClaudeBot?
The parser analyzes the User-Agent token signatures for known crawler patterns, such as Googlebot, Bingbot, GPTBot, ClaudeBot, PerplexityBot, and Applebot. When matched, it tags the client type as Bot / Crawler and displays the specific automated crawler identity alongside standard browser fields.
What is User-Agent Client Hints (UA-CH) and how does it replace legacy user-agent strings?
User-Agent Client Hints (UA-CH) is a modern web standard where browsers send minimal initial headers (such as Sec-CH-UA and Sec-CH-UA-Mobile) and only disclose detailed brand, architecture, or full platform versions if the server explicitly requests them via Accept-CH headers, preventing passive client fingerprinting.