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.

Header type Response header
Forbidden header name ?

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.


Accept-CH: <list of client hints>


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

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

Browser compatibility

BCD tables only load in the browser

See also