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http header

Sec-CH-UA-Arch header

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Limited availabilitySecure context

The HTTP Sec-CH-UA-Arch request header is a user 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](https://developer.mozilla.org/en-US/docs/Glossary/Request%20header), Client hint
[Forbidden request header](https://developer.mozilla.org/en-US/docs/Glossary/Forbidden%20request%20header) Yes (Sec- prefix)

Syntax

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 the Sec-CH-UA-Arch header by including the Accept-CH in a response to some request from the client, using the name of the desired header as a token:

HTTP/1.1 200 OK
Accept-CH: Sec-CH-UA-Arch

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

GET /my/page HTTP/1.1
Host: example.site

Sec-CH-UA: " Not A;Brand";v="99", "Chromium";v="96", "Google Chrome";v="96"
Sec-CH-UA-Mobile: ?0
Sec-CH-UA-Platform: "Windows"
Sec-CH-UA-Arch: "x86"

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

Specifications

SpecificationsStandards references are available on the canonical MDN page.

Browser compatibility

Browser compatibilityCompatibility data is available on the canonical MDN page.

See also