Client Hints test
Chromium browsers describe themselves twice: in the old User-Agent string and in Client Hints. This page shows both and checks that they tell the same story.
Checking your browser…
What Client Hints are
Chromium browsers (Chrome, Edge, Opera, Brave and others) describe themselves in two ways. The old User-Agent string is one line of text. User-Agent Client Hints are structured: brands and their versions, whether it is a phone, the platform, and on request more detail such as the platform version, CPU architecture, bitness, device model and the full version of every brand.
Part of the hints travels in the request headers (Sec-CH-UA, Sec-CH-UA-Mobile, Sec-CH-UA-Platform), the rest is read in JavaScript through navigator.userAgentData. This page shows both and checks them against the User-Agent string. Firefox and Safari do not support Client Hints.
How to read the result
- Brands: the low-entropy list every page gets, including a deliberate fake brand that keeps sites from relying on the order.
- Full versions and platformVersion: the high-entropy values. On Windows a platform version of 13 or higher means Windows 11; the User-Agent string says Windows NT 10.0 for both 10 and 11.
- Sec-CH-UA headers: what the browser sent with the request; they must agree with what JavaScript reports.
- Verdict: a red result means the hints contradict the User-Agent, the platform or the headers, a common seam of spoofing tools.
Further reading
- User-Agent Client Hints explained
- What browser fingerprinting is and how it works
- How the truth index is calculated
Frequently asked questions
- How do I tell Windows 10 from Windows 11 in the browser?
- Through Client Hints: platformVersion 13 or higher is Windows 11. The User-Agent string cannot tell them apart.
- Why does the list contain a strange brand like "Not?A_Brand"?
- Chromium adds a made-up brand on purpose so that sites do not depend on an exact list. It is normal.
- My browser is Chrome but the page says Client Hints are missing.
- Some privacy extensions and in-app browsers turn them off. Then sites see only the User-Agent string.
- Is anything stored?
- No. The values are read for this check and forgotten; only daily sums are counted, without the checks themselves.