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.

See full compatibility

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 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, 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 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

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:

http

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

Specification
User-Agent Client Hints # sec-ch-ua-arch

Browser compatibility

	desktop					mobile
	Chrome	Edge	Firefox	Opera	Safari	Chrome Android	Firefox for Android	Opera Android	Safari on iOS	Samsung Internet	WebView Android	WebView on iOS
`Sec-CH-UA-Arch` request header Experimental	Chrome – Full support Chrome 89 (Release date: 2021-03-02) footnote Full support	Edge – Full support Edge 89 (Release date: 2021-03-04) footnote Full support	Firefox – No support Firefox footnote No support	Opera – Full support Opera 75 (Release date: 2021-03-24) footnote Full support	Safari – No support Safari footnote No support	Chrome Android – Full support Chrome Android 89 (Release date: 2021-03-02) footnote Full support	Firefox for Android – No support Firefox for Android footnote No support	Opera Android – Full support Opera Android 63 (Release date: 2021-04-16) footnote Full support	Safari on iOS – No support Safari on iOS footnote No support	Samsung Internet – Full support Samsung Internet 23 (Release date: 2023-10-18) footnote Full support	WebView Android – Full support WebView Android 89 (Release date: 2021-03-02) footnote Full support	WebView on iOS – No support WebView on iOS footnote No support

Tip: you can click/tap on a cell for more information.

Full support: Full support
No support: No support
: Experimental. Expect behavior to change in the future.

Sec-CH-UA-Arch header

Syntax

Directives

Examples

Using Sec-CH-UA-Arch

Specifications

Browser compatibility

Legend

See also