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.

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