Permissions-Policy: ch-ua-high-entropy-values directive

Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

The HTTP Permissions-Policy header ch-ua-high-entropy-values directive controls whether or not the document is permitted to use the NavigatorUAData.getHighEntropyValues() method to retrieve high-entropy user-agent data.

If the permission is not allowed, the method will only return the brands, mobile, and platform low-entropy data.

Syntax

http
Permissions-Policy: ch-ua-high-entropy-values=<allowlist>;
<allowlist>

A list of origins for which permission is granted to use the feature. See Permissions-Policy > Syntax for more details.

Default policy

The default allowlist for ch-ua-high-entropy-values is *.

Examples

Restricting high-entropy data to specific origins

The following policy would only allow the current origin and two other specific origins to retrieve high-entropy data.

http
Permissions-Policy: ch-ua-high-entropy-values=("self https://a.example.com" "https://b.example.com")

You could then embed one of the two other origins:

html
<iframe src="https://a.example.com" allow="ch-ua-high-entropy-values"></iframe>

Specifications

Specification
User-Agent Client Hints
# ch-ua-high-entropy-values

Browser compatibility

desktop mobile
Chrome
Edge
Firefox
Opera
Safari
Chrome Android
Firefox for Android
Opera Android
Safari on iOS
Samsung Internet
WebView Android
WebView on iOS
ch-ua-high-entropy-values
Experimental
Chrome – Full support
Chrome 144 (Release date: 2026-01-13)
footnote Full support
Edge – Full support
Edge 144 (Release date: 2026-01-21)
footnote Full support
Firefox – No support
Firefox
footnote No support
Opera – Full support
Opera 128 (Release date: 2026-02-26)
footnote Full support
Safari – No support
Safari
footnote No support
Chrome Android – No support
Chrome Android
footnote No support
Firefox for Android – No support
Firefox for Android
footnote No support
Opera Android – No support
Opera Android
footnote No support
Safari on iOS – No support
Safari on iOS
footnote No support
Samsung Internet – No support
Samsung Internet
footnote No support
WebView Android – No support
WebView Android
footnote No support
WebView on iOS – No support
WebView on iOS
footnote No support

Legend

Tip: you can click/tap on a cell for more information.

Full support
Full support
No support
No support
Experimental. Expect behavior to change in the future.

See also