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/HTTP

Accept-CH

Secure context
This feature is available only in secure contexts (HTTPS), in some or all supporting browsers.

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

The Accept-CH header is set by the server to specify which Client Hints headers a client should include in subsequent requests.

Note: Client Hints are accessible only on secure origins (via TLS). Accept-CH and Accept-CH-Lifetime headers should be persisted for all secure requests to ensure Client Hints are sent reliably.

Syntax

Accept-CH: <list of client hints>

Examples

Accept-CH: DPR, Viewport-Width
Accept-CH: Width
Accept-CH-Lifetime: 86400
Vary: DPR, Viewport-Width, Width

Note: Remember to vary the response based on the accepted client hints.

Browser compatibilityUpdate compatibility data on GitHub

Desktop
Chrome Edge Firefox Internet Explorer Opera Safari
Accept-CH 46 ≤79 ? ? 33 ?
DPR 46 ≤79 ? ? 33 ?
Viewport-Width 46 ≤79 ? ? 33 ?
Width 46 ≤79 ? ? 33 ?
Mobile
Android webview Chrome for Android Firefox for Android Opera for Android Safari on iOS Samsung Internet
Accept-CH 46 46 ? 33 ? 5.0
DPR 46 46 ? 33 ? 5.0
Viewport-Width 46 46 ? 33 ? 5.0
Width 46 46 ? 33 ? 5.0

See also

© 2005–2020 Mozilla and individual contributors.
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Accept-CH