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-Full-Version-List user agent client hint request header provides the user-agent's branding and full version information.

Header type Request header, Client hint
Forbidden header name yes

The Sec-CH-UA-Full-Version-List header provides the brand and full version information for each brand associated with the browser, in a comma-separated list.

A brand is a commercial name for the user agent like: Chromium, Opera, Google Chrome, Microsoft Edge, Firefox, and Safari. A user agent might have several associated brands. For example, Opera, Chrome, and Edge are all based on Chromium, and will provide both brands in the Sec-CH-UA-Full-Version-List header.

The header therefore allows the server to customise its response based on both shared brands and on particular customisations in their specific respective builds.

The header may include "fake" brands in any position and with any name. This is a feature designed to prevent servers from rejecting unknown user agents outright, forcing user agents to lie about their brand identity.

Note: This is similar to Sec-CH-UA, but includes the full version number instead of the significant version number for each brand.


A comma separated list of brands in the user agent brand list, and their associated full version number. The syntax for a single entry has the following format:

Sec-CH-UA-Full-Version-List: "<brand>";v="<full version>", ...



A brand associated with the user agent, like "Chromium", "Google Chrome", or an intentionally incorrect brand like "Not A;Brand".

<full version>

A full version number, such as 98.0.4750.0.


A server requests the Sec-CH-UA-Full-Version-List 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-Full-Version-List

The client may choose to provide the hint, and add the Sec-CH-UA-Full-Version-List header to subsequent requests, as shown below:

GET /my/page HTTP/1.1

Sec-CH-UA: " Not A;Brand";v="99", "Chromium";v="98", "Google Chrome";v="98"
Sec-CH-UA-Mobile: ?0
Sec-CH-UA-Full-Version-List: " Not A;Brand";v="", "Chromium";v="98.0.4750.0", "Google Chrome";v="98.0.4750.0"
Sec-CH-UA-Platform: "Linux"


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Browser compatibility

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See also