What is My User Agent? - Free Online Checker

User Agent Guide

Why Check Your User Agent String?

Knowing your user agent string gives you insight into exactly how your browser identifies itself to every server on the internet. Here are the most common reasons to check it:

• Web Development & QA: Verify how your browser is detected by sites and test browser-specific conditional logic, redirects, or feature flags.
• Troubleshooting Compatibility: Diagnose why a site behaves differently in your browser by seeing exactly what UA string it receives.
• Privacy Analysis: Understand what information your browser automatically broadcasts to every website you visit — without your explicit consent.
• Feature & API Detection: Confirm which browser capabilities and supported technologies your current setup reports.
• Security Research: Analyze browser fingerprinting vectors and understand how user agent sniffing is used in tracking and targeting.
• Automated Testing: Check the UA string your headless browser or test runner presents when running integration tests.

What Does a User Agent String Look Like?

A typical user agent string can look intimidatingly long, but each part has a specific meaning. Here is a real example from Chrome on Windows:

• Mozilla/5.0 — A legacy compatibility token. All modern browsers include this regardless of the actual browser.
• (Windows NT 10.0; Win64; x64) — The operating system (Windows 10/11), architecture (64-bit).
• AppleWebKit/537.36 — The rendering engine. Chrome is based on Blink, which derived from WebKit.
• (KHTML, like Gecko) — Another compatibility token, signalling compatibility with Gecko-based parsers.
• Chrome/124.0.0.0 — The actual browser name and version.
• Safari/537.36 — Included for historical compatibility with servers that check for Safari.

How to Use This User Agent Checker

No setup needed — your user agent is detected and displayed automatically the moment you open the page. Here is what each step shows you:

Step 1 — Your UA String Is Auto-Detected

The full raw user agent string sent by your browser is shown at the top of the tool card. This is the exact string every website you visit receives.

Step 2 — Review Browser & System Details

The Browser Information and System Information panels break down your browser name, version, rendering engine, operating system, OS version, architecture, and device type.

Step 3 — Check Browser Capabilities

The Capabilities panel confirms whether JavaScript, cookies, LocalStorage, and WebGL are enabled and available in your current session.

Step 4 — Run Feature Tests

Click Test Features to run an extended suite of browser API tests — geolocation, WebSockets, IndexedDB, CSS transforms, touch events, service workers, and more.

Step 5 — Copy or Inspect the Raw Data

Use Copy User Agent to copy the string to your clipboard instantly. Click View Parsed Details to see the full parsed JSON object for use in debugging or reporting.

Understanding User Agent Strings

A User Agent string is a text identifier that your web browser sends to every website you visit. It contains information about your browser type, version, operating system, and device. Web developers use this information to ensure websites display correctly across different browsers and devices.

What Information Does Your User Agent Reveal?

• Browser Information: The name and version of your web browser (Chrome, Firefox, Safari, Edge, Opera, etc.).
• Operating System: Your operating system and version (Windows, macOS, Linux, iOS, Android).
• Device Type: Whether you're using a desktop, mobile device, tablet, or other hardware.
• Rendering Engine: The engine used to display web pages (Blink, WebKit, Gecko, Trident).
• Architecture: Your device's processor architecture (x86, x64, ARM).

How User Agents Work

Every time your browser requests a web page, it includes the User Agent string in the HTTP headers. Websites use this information to serve appropriate content, apply browser-specific CSS fixes, enable or disable features based on browser capabilities, and provide mobile-optimized versions for mobile devices. Server-side code, analytics platforms, and ad networks all read this string to make decisions about what to show you.

User Agent Structure

User Agent strings follow a specific format that includes the browser name, version, operating system, and various compatibility tokens. Modern browsers often include multiple identifiers for backwards compatibility, which is why User Agent strings can appear complex and contain seemingly redundant information. The Mozilla/5.0 prefix, for example, is present in virtually every modern browser even though none of them are actually Mozilla — it persists purely for legacy server compatibility.

Privacy Considerations

While User Agent strings are essential for web compatibility, they can also be used for browser fingerprinting to track users across websites. Combined with other signals like screen resolution, timezone, and installed fonts, your UA string contributes to a unique digital fingerprint. Modern browsers are working to freeze or reduce UA granularity — Chrome's User-Agent Client Hints (UA-CH) initiative is gradually replacing the traditional UA string with a privacy-preserving alternative.

Frequently Asked Questions

What is a user agent string?

A user agent string is a short line of text that your browser automatically sends in every HTTP request. It identifies your browser type, version, rendering engine, and operating system to the server so the site can deliver compatible content. For example: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 Chrome/124.0.0.0.

Can websites see my user agent?

Yes — every website you visit receives your user agent string automatically as part of the HTTP request headers. You don't need to opt in or take any action; it is sent by default by all browsers. This is why tools like this one can display it instantly without any server-side lookup.

How do I change my user agent?

In Chrome and Edge, open DevTools (F12), click the three-dot menu → More tools → Network conditions, then uncheck "Use browser default" and enter a custom UA string. In Firefox, type about:config in the address bar, search for general.useragent.override, and set your custom value. Browser extensions like "User-Agent Switcher" can also rotate UA strings automatically.

Why does my user agent show a different browser version?

Some browsers freeze or reduce UA version numbers to improve privacy. Chrome has gradually frozen minor version numbers (showing 0.0.0 for build details). Brave browser spoofs its UA to match Chrome. If your UA version looks truncated or generic, your browser may be participating in the UA reduction initiative.

Is checking my user agent safe?

Completely. This tool reads your user agent string using the browser's built-in navigator.userAgent property — everything runs locally in your browser with no data sent to any server. Nothing is stored, logged, or shared.

What is user agent sniffing?

User agent sniffing (also called browser detection) is the practice of reading the UA string on the server or in JavaScript to serve different content or code paths to different browsers. While once common for handling IE quirks, it is now discouraged in favour of feature detection (e.g. checking if IntersectionObserver exists rather than checking if the browser is Chrome). UA sniffing is fragile because UA strings change frequently and can be spoofed.

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