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Sec-CH-Device-Memory header

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

The HTTP Sec-CH-Device-Memory request header is used in device client hints to indicate the approximate amount of available RAM on the client device, in gigabytes. The header is part of the Device Memory API.

Client hints are accessible only on secure origins. A server has to opt in to receive the Sec-CH-Device-Memory header from the client, by first sending the Accept-CH response header. Servers that opt in to the Sec-CH-Device-Memory client hint will typically also specify it in the Vary header to inform caches that the server may send different responses based on the header value in a request.

Header type Request header, Client hint
Forbidden request header No

Syntax

http
Sec-CH-Device-Memory: <number>

Directives

<number>

The approximate amount of device RAM. Possible values are: 0.25, 0.5, 1, 2, 4, 8. The amount of device RAM can be used as a fingerprinting variable, so values for the header are intentionally coarse to reduce the potential for its misuse.

Examples

The server first needs to opt in to receive Sec-CH-Device-Memory header by sending the Accept-CH response header containing Sec-CH-Device-Memory:

http
Accept-CH: Sec-CH-Device-Memory

Then on subsequent requests the client might send Sec-CH-Device-Memory header back:

http
Sec-CH-Device-Memory: 1

Specifications

This feature does not appear to be defined in any specification.

Browser compatibility

See also

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