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Client hints a browser can return

Client hints a browser can return?

Navigator userAgentData can expose brands, mobile, and platform without a prompt, and the experimental getHighEntropyValues method adds architecture, bitness, formFactors, fullVersionList, model, platformVersion, and wow64 only when the page is allowed to read those hints. A denied permission returns only brands, mobile, and platform.

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Navigator userAgentData can expose brands, mobile, and platform without a prompt, and the experimental getHighEntropyValues method adds architecture, bitness, formFactors, fullVersionList, model, platformVersion, and wow64 only when the page is allowed to read those hints. A denied permission returns only brands, mobile, and platform.

Last checked 2026-10-22

Two groups

MDN says the object returned by getHighEntropyValues includes the low-entropy brands, mobile, and platform values by default, plus the high-entropy hints that were requested and permitted. Low-entropy hints are the ones described as unlikely to fingerprint. High-entropy hints are the ones described as more likely to.

High-entropy names in that document are architecture, bitness, formFactors, fullVersionList, model, platformVersion, uaFullVersion, and wow64. If Permissions-Policy ch-ua-high-entropy-values is not allowed, only brands, mobile, and platform are returned. Node has no navigator.userAgentData, so a server-side script cannot stand in for the tab.

Where to read them

The headless dump on this machine returned the brand string Not A(Brand) at low-entropy version 99 and full version 99.0.0.0, next to Chromium and Google Chrome at 154 and 154.0.8037.92. MDN says one object in fullVersionList may intentionally contain invalid information so sites cannot rely on a fixed list of browsers. The model was an empty string, which MDN says is what you get when the device is not a mobile device or the model is not known. The empty platformVersion is what that process returned.

Press Read this tab on WebGL, WebGPU, and client hints. The report is not uploaded.

Sources

Last checked 2026-10-22.

Questions

What did one headless Chrome return?

On qiang-pro, headless Chrome reported brands Chromium 154, Google Chrome 154, and Not A(Brand) 99, mobile false, and platform Linux. The high-entropy result added architecture x86, bitness 64, formFactors Desktop, full versions 154.0.8037.92, 154.0.8037.92, and 99.0.0.0, an empty model, an empty platformVersion, uaFullVersion 154.0.8037.92, and wow64 false. That is one Linux process, not your browser.

Is uaFullVersion current?

MDN marks uaFullVersion deprecated in favor of fullVersionList. The button still requests it so you can see whether this browser returns it.

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