Sec-CH-UA-Form-Factors
Secure context: This feature is available only in secure contexts (HTTPS), in some or all supporting browsers.
Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.
The HTTP Sec-CH-UA-Form-Factors
request header is a user agent client hint which provides information on the user-agent's device form factor.
Header type | Request header, Client hint |
---|---|
Forbidden header name | Yes (Sec- prefix) |
Syntax
Sec-CH-UA-Form-Factors: <form-factor>
Sec-CH-UA-Form-Factors: <form-factor>, …, <form-factor>
Directives
<form-factor>
-
A string indicating a common device form factor. All applicable form factors can be included. The meanings of the allowed values are:
"Desktop"
-
A user-agent running on a personal computer.
"Automotive"
-
A user-agent embedded in a vehicle, where the user may be responsible for operating the vehicle and have limited ability to interact.
"Mobile"
-
Small, touch-oriented device typically carried on a user's person.
"Tablet"
-
A touch-oriented device larger than
"Mobile"
and not typically carried on a user's person. "XR"
-
Immersive devices that augment or replace the environment around the user.
"EInk"
-
A device characterized by slow screen updates and limited or no color resolution.
"Watch"
-
A mobile device with a tiny screen (typically less than 2 inches), carried in such a way that the user can glance at it quickly.
Examples
Using Sec-CH-UA-Form-Factors
A server requests the Sec-CH-UA-Form-Factors
header by including the Accept-CH
in a response to any request from the client, using the name of the desired header as a token:
HTTP/1.1 200 OK
Accept-CH: Sec-CH-UA-Form-Factors
The client may choose to provide the hint, and add the Sec-CH-UA-Form-Factors
header to subsequent requests.
For example, the client might add the header as shown:
GET /my/page HTTP/1.1
Host: example.site
Sec-CH-UA-Mobile: ?0
Sec-CH-UA-Form-Factors: "EInk"
In this case, "EInk"
means that the device is characterized by slow screen updates and limited color resolution, and as such, responses may differ depending on this hint.
Specifications
Specification |
---|
User-Agent Client Hints # sec-ch-ua-form-factors |
Browser compatibility
Report problems with this compatibility data on GitHubdesktop | mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
Sec-CH-UA-Form-Factors request header |
Legend
Tip: you can click/tap on a cell for more information.
- Full support
- Full support
- No support
- No support
- Experimental. Expect behavior to change in the future.
See also
- Client hints
- User-Agent Client Hints API
Accept-CH
- HTTP Caching: Vary and
Vary
header - Improving user privacy and developer experience with User-Agent Client Hints on developer.chrome.com