Sec-CH-UA-Mobile

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-Mobile request header is a user agent client hint which indicates whether the browser is on a mobile device. It can also be used by a desktop browser to indicate a preference for a "mobile" user experience.

Sec-CH-UA-Mobile 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- prefix)

Syntax

http
Sec-CH-UA-Mobile: <boolean>

Directives

<boolean>

?1 indicates that the user-agent prefers a mobile experience (true). ?0 indicates that user-agent does not prefer a mobile experience (false).

Examples

Using Sec-CH-UA-Mobile

As Sec-CH-UA-Mobile is a low entropy hint it is typically sent in all requests. A desktop browser would usually send requests with the following header:

http
Sec-CH-UA-Mobile: ?0

A browser on a mobile device would usually send requests with the following header:

http
Sec-CH-UA-Mobile: ?1

Specifications

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

Browser compatibility

BCD tables only load in the browser

See also