What Version of macOS Do I Have
See which macOS version your browser reports, read from your user agent.
Nothing is sent to a server; this is read and shown entirely in your browser.
What is What Version of macOS Do I Have?
Reads the macOS version straight out of your browser's user agent string — a quick check without opening the Apple menu → About This Mac → System Settings. Useful for confirming compatibility before installing software, or for including your OS version in a support request or bug report. The check happens entirely client-side: your browser exposes an OS version in its user agent, this page parses it with JavaScript, and nothing is sent to a server. Note that macOS's user agent string has historically lagged behind the actual OS release in some browsers (showing an older major version number even after an update), so treat this as a strong hint rather than an authoritative source — About This Mac is always the ground truth.
FAQ
Either you're not on a Mac, or your browser sends a generic user agent for privacy, which is increasingly common.
Some browsers cap or freeze the macOS version reported in their user agent string for compatibility reasons, so it can lag behind your real OS version. Check Apple menu → About This Mac for the definitive answer.
No. Detection happens locally by parsing `navigator.userAgent` in your browser; nothing is transmitted.