check your screen resolution
Your screen size, viewport, pixel ratio, and display settings.
See the user agent string your browser sends to every website, broken down into browser, engine, operating system, and device. You can also paste any other user agent to parse it.
Your browser sends a User-Agent header with every request, and scripts can read the same text as navigator.userAgent. This page reads it in your browser; the server never looks at it, so the page itself stays the same for everyone.
The parser checks tokens in a fixed order, because browsers copy each other's names for compatibility. Chrome's string also says "Safari", and Edge's says "Chrome" and "Safari". So Edge (Edg/) is checked before Chrome, and Chrome before Safari. Every browser on iPhone and iPad uses Apple's WebKit engine, so the engine is always WebKit there, even for Chrome (CriOS) and Firefox (FxiOS).
In Chromium browsers the page also asks for User-Agent Client Hints through navigator.userAgentData. They report the exact browser version, the platform version (Windows 11 reports 13 or higher), the CPU architecture, and the device model.
Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/124.0.0.0 Safari/537.36 Edg/124.0.2478.80: Microsoft Edge 124, Blink, Windows 10 or 11, desktop.Mozilla/5.0 (iPhone; CPU iPhone OS 17_4 like Mac OS X) ... Version/17.4 Mobile/15E148 Safari/604.1: Safari 17.4, WebKit, iOS 17.4, mobile.Mozilla/5.0 (Linux; Android 10; K) ... Chrome/124.0.0.0 Mobile Safari/537.36: Chrome 124 on Android, mobile. The "10" and "K" are frozen placeholders.A short text your browser sends with every request, naming the browser, its engine, and the operating system. Sites use it for statistics, bug workarounds, and to offer the right download.
For compatibility. Old sites sent full pages only to browsers they recognized, so new browsers copied the tokens of older ones. Almost every browser still starts with Mozilla/5.0.
Browsers send Windows NT 10.0 for both. Chromium browsers can report Windows 11 through client hints, shown in the table on this page.
Yes. Browser developer tools can override it (in Chrome: DevTools, then Network conditions), and extensions can switch it. Sites then see the string you chose.
Often used together with the What Is My User Agent.
Your screen size, viewport, pixel ratio, and display settings.
Builds copy-ready cURL commands with headers, auth, and a body, quoted for your shell.
Pulls every valid IPv4 and IPv6 address out of any text.