Sec-CH-UA-Arch header

Limited availability

This feature is not Baseline because it does not work in some of the most widely-used browsers.

Experimental:This is anexperimental technology
Check theBrowser compatibility table carefully before using this in production.

Secure context: This feature is available only insecure contexts (HTTPS), in some or allsupporting browsers.

The HTTPSec-CH-UA-Archrequest header is auser agent client hint which contains the user-agent's underlying CPU architecture, such as ARM or x86.

This might be used by a server, for example, to select and offer the correct binary format of an executable for a user to download.

Header type	Request header,Client hint
Forbidden request header	Yes (`Sec-` prefix)

Syntax

http

Sec-CH-UA-Arch: <arch>

Directives

<arch>: A string indicating the underlying platform architecture, such as:"x86","ARM","[arm64-v8a, armeabi-v7a, armeabi]".

Examples

Using Sec-CH-UA-Arch

A server requests theSec-CH-UA-Arch header by including theAccept-CH in a response to some request from the client, using the name of the desired header as a token:

http

HTTP/1.1 200 OKAccept-CH: Sec-CH-UA-Arch

The client may choose to provide the hint, and add theSec-CH-UA-Arch header to subsequent requests.For example, on a Windows X86 based computer, the client might add the header as shown:

http

GET /my/page HTTP/1.1Host: example.siteSec-CH-UA: " Not A;Brand";v="99", "Chromium";v="96", "Google Chrome";v="96"Sec-CH-UA-Mobile: ?0Sec-CH-UA-Platform: "Windows"Sec-CH-UA-Arch: "x86"

Note above that thelow entropy headers are added to the request even though not specified in the server response.