Browser Info & User Agent Checker

What Is a User Agent?

A user agent is a text string your browser sends with every request, identifying itself, its version, its rendering engine, and your operating system. Websites use it to decide things like which layout to serve, whether to show a mobile or desktop experience, or to flag outdated browsers that might not support certain features. It's essentially your browser introducing itself to every server it talks to, a practice that dates back to the earliest days of the web when servers needed a way to know what kind of client was requesting content.

Why Would I Need to Check This?

Developers use it to debug browser-specific bugs, support teams use it to diagnose issues reported by users, and anyone troubleshooting a site behaving oddly can check whether their browser or OS is outdated. It's also a quick way to confirm which browser and version you're actually running, especially on devices where multiple browsers look nearly identical, or where a browser has been rebranded or forked from another engine and the true underlying browser isn't obvious from the interface alone.

Anatomy of a User Agent String

A typical user agent string looks dense and confusing at first glance, but it follows a fairly consistent structure. It usually starts with a compatibility token, historically "Mozilla/5.0" for almost all modern browsers, a legacy holdover from the early browser wars that has stuck around for compatibility reasons even though it no longer reflects an actual Mozilla browser in most cases. This is followed by platform information in parentheses, covering the operating system and sometimes hardware architecture. After that comes rendering engine information, like WebKit or Gecko, and finally the specific browser name and version. Multiple browser and engine names often appear together in a single string, since many modern browsers are built on shared underlying engines, which is part of why user agent strings can look longer and more layered than expected.

Browser Fingerprinting: How User Agent Contributes

User agent is one of several data points websites can use to build a browser fingerprint, a combination of characteristics, screen size, installed fonts, timezone, language settings, and more, that together can identify a specific browser instance with surprising precision, even without cookies. On its own, a user agent string is fairly generic, since many people share the identical browser and OS combination, but combined with other signals it becomes a meaningfully more unique identifier. This is why privacy-focused browsers and browser extensions sometimes deliberately simplify or freeze the reported user agent to a small number of common values, reducing how much it contributes to fingerprinting compared to a fully detailed, unique-looking string.

User Agent Spoofing: Why and How It's Done

Because the user agent is simply a string the browser chooses to report, it can be changed, or spoofed, fairly easily, through browser developer tools, extensions, or command-line flags. Developers commonly spoof their user agent temporarily to test how a website behaves for different browsers or devices without needing physical access to each one, a legitimate and common testing practice. Some users also spoof their user agent to access websites that unnecessarily block certain browsers, or to reduce how uniquely identifiable their browsing fingerprint appears. Because spoofing is so accessible, no website should treat a user agent string as a fully trustworthy or tamper-proof signal.

Do Not Track: What It Actually Does

The Do Not Track (DNT) setting is a browser preference that, when enabled, sends a signal to websites requesting that they not track browsing activity across sites. Despite the name, DNT is a request, not an enforceable technical restriction. Compliance with it is entirely voluntary on the part of each website, and support for honoring the signal has become inconsistent enough over the years that some major browsers have actually removed the setting from their interface, considering it more of a false sense of privacy than a meaningful protection. Checking whether it's enabled here mainly serves informational and troubleshooting purposes rather than being a reliable privacy safeguard on its own.

Cookies and Why They Matter for Browsing

Whether cookies are enabled affects how websites remember information about a visit, from staying logged into an account to remembering items in a shopping cart between page loads. Most websites require cookies enabled for core functionality like logging in, and some display a warning or fail to work correctly if cookies are disabled. Browsers increasingly distinguish between different types of cookies, first-party cookies set by the site being visited directly, and third-party cookies set by other domains embedded within a page, often used for cross-site advertising tracking, with many modern browsers now blocking third-party cookies by default while still allowing first-party ones needed for basic site functionality.

Common Browsers and Their Rendering Engines

Most modern browsers are built on one of a small number of underlying rendering engines, the software component responsible for turning HTML and CSS into what actually appears on screen. Chrome, Edge, Opera, and many other browsers use Blink, an engine originally forked from WebKit. Safari uses WebKit directly. Firefox uses its own independent engine called Gecko. This shared-engine landscape is why many browsers built on the same underlying engine behave nearly identically for most websites, even though they present different branding, features, and user interfaces, and it's also why user agent strings from Blink-based browsers often look structurally similar to each other despite representing entirely different products.

Language Preference: How Websites Use navigator.language

The language value reported here reflects the browser's configured display language, typically inherited from operating system settings, and is commonly used by websites to automatically serve content in a visitor's preferred language without requiring an explicit selection. This is convenient but not always perfectly accurate. Someone using a browser configured in English while actually preferring content in another language, perhaps on a shared or borrowed device, would still see English-language defaults based on this setting. Most well-built multilingual websites offer a manual language switcher precisely because automatic detection from this single browser setting doesn't always match a visitor's actual preference.

Hardware Concurrency: What CPU Core Count Reveals

The CPU core count shown here comes from a browser API called hardware concurrency, which reports an approximate number of logical processor cores available to the browser. Websites and web applications sometimes use this figure to decide how much parallel processing work they can safely perform in the browser, such as splitting a computationally heavy task across multiple background threads for better performance on more capable hardware, while scaling back on lower-powered devices. This value is described as approximate because some browsers deliberately cap or round the reported figure for privacy reasons, to avoid this hardware detail contributing too precisely to browser fingerprinting.

Checking Browser Compatibility Before Building a Website

For anyone building or maintaining a website, understanding what information is available through the navigator object, the same data this tool displays, is foundational to writing code that behaves correctly across different browsers. Rather than assuming every visitor uses the same browser as the one used during development, careful developers test against multiple real browsers and consult browser compatibility references before relying on newer web features, since not every browser adopts new capabilities at the same pace. A quick check of this page's own results across a few different browsers is a simple, practical way to see firsthand how differently browsers can report even basic information like platform and language.

How Websites Use This Data to Serve Different Experiences

Beyond simple browser detection, sites use navigator data to make practical decisions: serving a mobile-optimized layout to phone browsers, offering a download link matching the visitor's operating system, warning users on outdated or unsupported browsers that certain features may not work correctly, and adjusting default language or regional settings based on the browser's reported language preference. None of this requires the user to explicitly state their device or preferences; it happens automatically based on the same navigator information this tool displays directly.

Online Status: What navigator.onLine Actually Detects

The online status shown here reflects whether the browser believes it currently has network connectivity, based on the operating system's network interface status, not necessarily confirmed access to the internet at large. This distinction matters because a device can be technically connected to a WiFi network, which the browser reports as online, while that network itself has no actual internet access, a scenario this simple check can't distinguish. Web applications sometimes use this signal to adjust behavior, like queuing actions to sync once a connection is confirmed restored, but robust applications generally verify actual server reachability separately rather than relying purely on this browser-reported flag.

Why Multiple Browsers on the Same Device Can Show Different Results

Running this tool in different browsers installed on the identical device, Chrome versus Firefox on the same laptop, for instance, will show different results for browser name, user agent string, and sometimes even hardware concurrency, despite both running on the same underlying hardware and operating system. This happens because each browser independently determines and reports its own values for these navigator properties, and different browsers can apply different privacy protections, rounding behaviors, or default settings even when measuring conceptually the same underlying hardware or software environment. This is a normal and expected outcome of browser diversity, not an inconsistency or error in either browser's reporting.

Frequently Asked Questions

Can websites fake or ignore my user agent?

Yes, in both directions, a user can spoof their user agent (browser extensions and dev tools make this easy), and websites can choose to ignore it entirely. It's a self-reported string, not a guaranteed fact, so it shouldn't be relied on for anything security-critical.

Does my user agent reveal personal information?

It reveals your browser, its version, your OS, and general device type, not your name, location, or identity. Combined with other data points like IP address, though, it can contribute to browser fingerprinting, which is why privacy-focused browsers sometimes simplify or "freeze" the reported user agent.

Is this information sent anywhere?

No, everything shown here is read directly from your browser's navigator object and displayed locally. Nothing is sent to a server.

Why does my browser's user agent mention other browser names I'm not using?

Many browsers are built on shared underlying engines and include compatibility tokens referencing other browsers for historical and compatibility reasons, so seeing Safari or Chrome mentioned in a different browser's user agent string doesn't necessarily mean that's the actual browser running.

Should I be worried if my user agent looks unusual or outdated?

An outdated browser version shown here is worth acting on, since older browsers can carry unpatched security vulnerabilities. Keeping a browser updated to its latest version is generally a simple, meaningful security improvement.

Can I permanently hide my user agent from every website?

Not entirely, since some minimal identifying information is generally needed for basic web functionality, but privacy-focused browser settings or extensions can simplify or standardize what's reported, reducing how uniquely identifiable it makes your browser.