Sec-CH-UA-Bitness header
Limited availability
This feature is not Baseline because it does not work in some of the most widely-used browsers.
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-Bitness request header is a user agent client hint which provides the "bitness" of the user-agent's underlying CPU architecture.
This is the size in bits of an integer or memory address—typically 64 or 32 bits.
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
Sec-CH-UA-Bitness: <bitness>
Directives
<bitness>-
A string indicating the underlying platform architecture bitness, such as:
"64","32".
Examples
Using Sec-CH-UA-Bitness
A server requests the Sec-CH-UA-Bitness header by including Accept-CH in a response to any request from the client, using the name of the desired header as a token:
HTTP/1.1 200 OK
Accept-CH: Sec-CH-UA-Bitness
The client may choose to provide the hint, and add the Sec-CH-UA-Bitness header to subsequent requests.
For example, on a Windows based 64-bit 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-Bitness: "64"
Specifications
| Specification |
|---|
| User-Agent Client Hints # sec-ch-ua-bitness |
Browser compatibility
| desktop | mobile | |||||||||||
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Sec-CH-UA-Bitness request header
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Legend
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.
See also
- Client hints
- User-Agent Client Hints API
Accept-CH- HTTP Caching: Vary and
Varyheader - Improving user privacy and developer experience with User-Agent Client Hints (developer.chrome.com)