Device-Memory

Experimental

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

Secure context

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

The Device-Memory device client hint request header field indicates the approximate amount of available RAM on the client device. The header is part of the Device Memory API.

Header type Request header, Client hint
Forbidden header name no

Note:

  • Client Hints are accessible only on secure origins (via TLS).
  • A server has to opt in to receive the Device-Memory header from the client, by sending the Accept-CH response header.
  • Servers that opt in to the Device-Memory client hint will typically also specify it in the Vary header. This informs caches that the server may send different responses based on the header value in a request.

Syntax

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 Device-Memory header by sending the response headers Accept-CH containing Device-Memory.

Accept-CH: Device-Memory

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

Device-Memory: 1

Specifications

Specification
Device Memory
# sec-device-memory-client-hint-header

Browser compatibility

BCD tables only load in the browser

See also