Windows 11 is only detectable with User-Agent Client Hints


1/13/2022 5:00 PM

Client Hints Microsoft Device Detection Version 4 Google Web

We’re disappointed that Microsoft communicated their sudden change so poorly

With the public release of Windows 11 on 5 October 2021, we were surprised to see that User Agent strings won't be updated to differentiate between Windows 11 and Windows 10. Rather, the only way to differentiate between the two is through User-Agent Client Hints.

Therefore, for users of our services, you need to upgrade your device detection to accurately detect this operating system. If you have not already done so, upgrade your services with us to version 4.4, which includes support for User-Agent Client Hints (UA-CH).

Get support for User-Agent Client Hints

We’re disappointed that Microsoft didn’t communicate their intentions beforehand (leading to further stress for web developers, rushing to support UA-CH to detect Windows 11). We’re also shocked to see that they were happy to adopt a change from Google that has yet to go through the usual Web standards process.

We’ve talked extensively about UA-CH, so let’s now talk about their responsibility within the Internet standardization process.


Internet standards should never be ignored

Google, through its Privacy Sandbox proposals, wants to remove the User-Agent string in favor of User-Agent Client Hints – their own HTTP header request.

The Web has been aware of UA-CH for a few years now, but the proposal doesn’t appear to have garnered sufficient support among other participants in the Open Web to have been standardized – either at the Internet Engineering Task Force (IETF) or the World Wide Web Consortium (W3C). And the reports written for the W3C on UA-CH, last updated on 10 December 2021, still reads as “unofficial draft”.

It seems to us that Google are bypassing the regular standardization process in order to push their experimental changes, all while expecting the rest of the Web to accommodate.

51Degrees is in correspondence with the UK Competition and Markets Authority (CMA) regarding the Privacy Sandbox proposals and changes to the use of the User-Agent header. Our version 4 software accomodates the changes introduced, however, it sets a worrying precedent for dominant companies to ignore established practice and impose proprietary changes to Internet standards and protocols.

After all, the last time we ignored Internet standards, we ended up with Internet Explorer.

The future of the Web

While there are only a few months left before Google begin to roll-out the User-Agent string reduction within Chromium-based browsers, other browsers and operating systems may follow suit. We were surprised by the sudden adoption of UA-CH by Microsoft, so it wouldn’t be shocking for others to do the same (but it would be unfortunate).

Our position in the matter is that we will support the Web as best as we can, while campaigning for better governance and equal standing between dominant companies and smaller market players. has been registered for the User-Agent Reduction origin trial with Chrome, so we can provide our feedback on the feature directly to Google.

Save yourself the headache of preparing for the User-Agent string reduction and User-Agent Client Hints – let our Device Detection do the hard work for you.

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