Sec-CH-UA-Platform header

The HTTP Sec-CH-UA-Platform request header is a user agent client hint which provides the platform or operating system on which the user agent is running. For example: "Windows" or "Android".

Sec-CH-UA-Platform is a low entropy hint. Unless blocked by a user agent permission policy, it is sent by default (without the server opting in by sending Accept-CH).

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-Platform: <platform>

Directives

<platform>
- : One of the following strings: "Android", "Chrome OS", "Chromium OS", "iOS", "Linux", "macOS", "Windows", or "Unknown".

Examples

Using Sec-CH-UA-Platform

As Sec-CH-UA-Platform is a low entropy hint it is typically sent in all requests. A browser running on a macOS computer might add the following header to all requests.

Sec-CH-UA-Platform: "macOS"

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