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 Sec-CH-UA-Platform user agent client hint request header 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, Client hint
Forbidden header name yes


Sec-CH-UA-Platform: <platform>



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


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"


User-Agent Client Hints
# sec-ch-ua-platform

Browser compatibility

BCD tables only load in the browser

See also