Device-Memory
Secure context: This feature is available only in secure contexts (HTTPS), in some or all supporting browsers.
The HTTP 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 Device-Memory
header from the client, by first 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 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 header name | No |
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 Accept-CH
response header 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 # iana-device-memory |
Browser compatibility
BCD tables only load in the browser
See also
- Improving user privacy and developer experience with User-Agent Client Hints (developer.chrome.com)
- Device Memory API
Navigator.deviceMemory
WorkerNavigator.deviceMemory
- Device client hints
Accept-CH
- HTTP Caching: Vary and
Vary