The Sec-CH-UA-Mobile user agent client hint header in the request specifies whether the browser is running on a mobile device. Additionally, a desktop browser uses it to signal a preference for a “mobile” user experience. The Sec-CH-UA-Mobile HTTP Header is a low-entropy hint. Low entropy suggestions include little information that may be used to “fingerprint” a certain person. It is delivered by default, without the server explicitly opting in via Accept-CH unless a user agent permission policy prohibits it. A server may set the Accept-CH header to indicate which client hint headers a client must include in subsequent requests. There is only one value for using the Sec-CH-UA-Mobile HTTP Header. The value for using the Sec-CH-UA-Mobile HTTP Header is boolean. An example of the Sec-CH-UA-Mobile HTTP Header is written below.

Sec-CH-UA-Mobile: ?0
Sec-CH-UA-Mobile: ?1

The Sec-CH-UA-Mobile HTTP Header Request Header is seen above. In the article, the Sec-CH-UA-Mobile HTTP Header Syntax, Directives, and Uses example will be processed.

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What is Sec-CH-UA-Mobile HTTP Header?

A user agent client hint header known as the Sec-CH-UA-Mobile HTTP Header identifies a mobile device as the source of the request. As a bonus, a desktop browser uses it to indicate that it prefers a “mobile” experience. A low entropy hint is the Sec-CH-UA-Mobile HTTP Header. A user agent permission policy does not prevent it from being supplied by default, and the server does not have to explicitly opt-in via Accept-CH.

What is the Syntax of Sec-CH-UA-Mobile HTTP Header?

The Sec-CH-UA-Mobile HTTP Header uses only one value. The syntax for using the Sec-CH-UA-Mobile HTTP Header is written below.

Sec-CH-UA-Mobile: <boolean>

What is the Directive of Sec-CH-UA-Mobile HTTP Header?

The Sec-CH-UA-Mobile HTTP Header only contains one directive. The boolean indicates by the number 1 that the user agent prefers a mobile experience (true). A value of 0 indicates that the user-agent does not prefer a mobile-friendly environment (false). An example directive for using the Sec-CH-UA-Mobile HTTP Header is given below.

Sec-CH-UA-Mobile: ?0
Sec-CH-UA-Mobile: ?1

How to use Sec-CH-UA-Mobile HTTP Header?

For mobile devices, the user agent client hint request header uses the Sec-CH-UA-Mobile HTTP Header as the user agent client hint request header. As a result, a desktop browser might use it to express a desire to have a more “mobile” experience. A low entropy hint is the Sec-CH-UA-Mobile HTTP Header. It is sent by default unless a user agent permission policy prevents it, and the server must explicitly opt-in by sending Accept-CH to do so.

Examples of Sec-CH-UA-Mobile HTTP Header Use

A low-entropy hint like Sec-CH-UA-Mobile HTTP Header is typically included in all requests. Requests from a desktop browser typically include the following header: Here’s an illustration of what I mean.

Sec-CH-UA-Mobile: ?0

The following headers are examples of requests sent by mobile browsers.

Sec-CH-UA-Mobile: ?1

What is the Specification Document for Sec-CH-UA-Mobile HTTP Header?

There is only one specification document for the Sec-CH-UA-Mobile HTTP Header, which is the User-Agent Client Hints. The User-Agent Client Hints article 3.5 mentions the Sec-CH-UA-Mobile HTTP Header’s definition and uses. Additionally, the article discusses the Sec-CH-UA-Mobile HTTP Header’s values and examples.

What is the type of Sec-CH-UA-Mobile HTTP Header?

The Sec-CH-UA-Mobile HTTP Header user agent client hint header is a type of Request Header that indicates whether or not the browser is running on a mobile device, such as a smartphone or tablet.

What are the similar HTTP Headers to the Sec-CH-UA-Mobile HTTP Header?

The similar HTTP Headers to the Sec-CH-UA-Mobile HTTP Header are listed below.

HTTP Client Hints: Servers can proactively request Client Hints from a client in order to obtain information about the device, network, user, and user-agent preferences of a given client. Similar to the Sec-CH-AU-Mobile HTTP Header, which is likewise a request header type.
User-Agent Client Hints API: A JavaScript API and a User-Agent response and request headers API are provided by the User-Agent Client Hints API, which extends the Client Hints API by exposing browser and platform information via User-Agent response and request headers. Similar to the Sec-CH-AU-Mobile HTTP Header, which is similarly a request header type.
Accept-CH HTTP Header: The Accept-CH HTTP Header is similar to the Sec-CH-UA-Mobile HTTP Header. Client hint headers may be included in subsequent requests if the Accept-CH HTTP Header is set by the server to define which client hint headers should be sent. Client hint headers are used in a manner similar to the Sec-CH-AU-Mobile HTTP Header.

Which Browsers Support Sec-CH-UA-Mobile HTTP Header?

There are multiple browsers that support Sec-CH-UA-Mobile HTTP Header. The following browsers are listed below.

Chrome Browser is compatible with the Sec-CH-UA-Mobile HTTP Header.
Edge Browser is compatible with the Sec-CH-UA-Mobile HTTP Header.
Opera Browser is compatible with the Sec-CH-UA-Mobile HTTP Header.
WebView Android Browser is compatible with the Sec-CH-UA-Mobile HTTP Header.
Chrome Android Browser is compatible with the Sec-CH-UA-Mobile HTTP Header.
Opera Android Browser is compatible with the Sec-CH-UA-Mobile HTTP Header.
Samsung Internet Browser is compatible with the Sec-CH-UA-Mobile HTTP Header.

You can see an image that shows the cross-browser compatibility of Sec-CH-UA-Mobile HTTP Headers below.

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