Sec-CH-UA-WoW64 header
Limited availability
This feature is not Baseline because it does not work in some of the most widely-used browsers.
Secure context: This feature is available only insecure contexts (HTTPS), in some or allsupporting browsers.
Experimental:This is anexperimental technology
Check theBrowser compatibility table carefully before using this in production.
The HTTPSec-CH-UA-WoW64request header is auser agent client hint indicating if a 32-bit user-agent application is running on a 64-bit Windows machine.
WoW64 was commonly used to know whichNPAPI plugin installer should be offered for download.This client hint header is used for backwards compatibility considerations, to provide a one-to-one mapping from the user-agent string of certain browsers to UA client hints.
| Header type | Request header,Client hint |
|---|---|
| Forbidden request header | Yes (Sec- prefix) |
Syntax
Sec-CH-UA-WoW64: <boolean>Directives
<boolean>?1indicates that the user agent's binary is running in 32-bit mode on 64-bit Windows (true), while?0means that it is not (false).
Examples
Using Sec-CH-UA-WoW64
A server requests theSec-CH-UA-WoW64 header by including theAccept-CH in aresponse to any request from the client, using the name of the desired header as a token:
HTTP/1.1 200 OKAccept-CH: Sec-CH-UA-WoW64The client may choose to provide the hint, and add theSec-CH-UA-WoW64 header to subsequent requests.AddingSec-CH-UA-WoW64: ?1 means the user agent's binary is running in 32-bit mode on 64-bit Windows:
GET /my/page HTTP/1.1Host: example.siteSec-CH-UA-WoW64: ?1Sec-CH-UA-Platform: "Windows"Sec-CH-UA-Form-Factors: "Desktop"Specifications
| Specification |
|---|
| User-Agent Client Hints # sec-ch-ua-wow64 |