Windows user agent tokens
Browsers on Windows include a Windows NT platform token in the legacy user-agent string. The NT version number has been effectively frozen, so it identifies the Windows family but not the marketing version — Windows 10 and Windows 11 share the same NT 10.0 token. Use Client Hints for finer platform detail.
What this means
On Windows, browsers embed a Windows NT platform token in the legacy user-agent string. The token indicates the Windows NT family. Historically the number tracked OS releases, but it has been frozen so that modern Windows reports the same NT 10.0 value regardless of whether the user runs Windows 10 or Windows 11.
This freeze is deliberate, both to reduce fingerprinting surface and to avoid breaking sites that hard-coded version checks. The practical effect is that the user agent confirms Windows but not the exact edition.
Why you cannot read the exact version
Because the NT number is frozen, parsing it to claim Windows 11 versus Windows 10 produces wrong results. The same applies to 32-bit versus 64-bit hints, which are also being reduced in modern Chromium.
If you genuinely need the platform version or architecture, use User-Agent Client Hints (Sec-CH-UA-Platform and high-entropy hints requested explicitly) rather than the legacy string, and accept that browsers may decline to provide high-entropy values.
- Token confirms the Windows family, not the marketing version
- Windows 10 and 11 both report NT 10.0
- Use Client Hints for finer, explicitly requested platform detail
Practical handling
For analytics, group Windows traffic by the broad family and resist presenting a precise version you cannot verify. If a chart shows a Windows version split derived purely from the user agent, it is likely inaccurate.
Never use the Windows token for access decisions on its own. It is OS context, and like all user-agent content it can be altered by the client.
How it appears in analytics and logs
A Windows NT token tells you the request came from a Windows desktop browser. The numeric version is frozen and does not distinguish Windows 10 from Windows 11, so do not report exact OS versions from the user agent alone.
Diagnostic use case
Interpret the Windows NT token correctly when analysing desktop platform share, and avoid claiming a precise Windows version the user agent cannot provide.
What WebmasterID can help detect
WebmasterID reads the Windows platform token as coarse OS context for human-traffic breakdowns, without over-claiming a specific Windows version or using the token as a fingerprinting input.
Common mistakes
- Reporting Windows 11 vs Windows 10 from the frozen NT token.
- Reading CPU architecture reliably from the legacy Windows user agent.
- Treating the platform token as a unique device fingerprint.
Privacy and accuracy notes
The platform token is coarse OS context, not a fingerprint or a location. WebmasterID records only the broad platform family and never combines tokens to single out a device.
Related pages
- macOS user agent tokens
Browsers on macOS include a Macintosh; Intel Mac OS X platform token. The macOS version embedded in it is frozen or capped by modern browsers, so it confirms macOS but not the precise release, and it still says Intel even on Apple Silicon for compatibility. Use Client Hints for finer detail.
- User-Agent Client Hints
User-Agent Client Hints are HTTP headers (the Sec-CH-UA family) that let a site request specific browser, platform, and version detail rather than reading it all from one passive string. They underpin UA reduction: the raw user agent is shrinking, and finer detail moves to opt-in hints. This page explains the model.
- User-agent reduction explained
User-agent reduction is Chrome's effort to freeze and trim the legacy user-agent string, removing fine-grained OS and full-version detail. The information is not gone; it moves to opt-in User-Agent Client Hints. This page explains what reduction changed and how detection should migrate to Client Hints.
- WebmasterID docs
How coarse platform context is recorded without fingerprinting.
Sources and verification notes
Last reviewed 2026-06-24. Facts are checked against primary/official sources where available; uncertain specifics are marked “Data not yet verified” rather than guessed.