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http header

Sec-CH-UA-Full-Version-List header

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The HTTP Sec-CH-UA-Full-Version-List request header is a user agent client hint which provides the user-agent’s branding and full version information.

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.

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.

Header type [Request header](https://developer.mozilla.org/en-US/docs/Glossary/Request%20header), Client hint
[Forbidden request header](https://developer.mozilla.org/en-US/docs/Glossary/Forbidden%20request%20header) Yes (Sec- prefix)

Syntax

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

The value is a comma separated list of brands in the user agent brand list, and their associated full version number.

Directives

  • <brand>
    • : A brand associated with the user agent, like “Chromium”, “Google Chrome”. This may be an intentionally incorrect brand like " Not A;Brand" or "(Not(A:Brand" (the actual value is expected change over time and be unpredictable).
  • <full version>
    • : A full version number, such as 98.0.4750.0.

Description

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 allows the server to customize its response based on both shared brands and on particular customizations in their specific respective builds.

Examples

Using Sec-CH-UA-Full-Version-List

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
Host: example.site

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="99.0.0.0", "Chromium";v="98.0.4750.0", "Google Chrome";v="98.0.4750.0"
Sec-CH-UA-Platform: "Linux"

Specifications

SpecificationsStandards references are available on the canonical MDN page.

Browser compatibility

Browser compatibilityCompatibility data is available on the canonical MDN page.

See also