Sec-Browsing-Topics header

WARNING: This feature is currently opposed by two browser vendors. See the Standards positions section for details of opposition.

NOTE: An Enrollment process is required to use this feature in your applications.

The HTTP Sec-Browsing-Topics request header sends the selected topics for the current user along with the associated request, which are used by an ad tech platform to choose a personalized ad to display.

If the calling site does not have the Topics API included in a successful privacy sandbox enrollment process, attempting to create or modify Sec-Browsing-Topics fails silently, and any existing Sec-Browsing-Topics header is deleted.

Syntax

Sec-Browsing-Topics: <array-of-observed-topics>

Directives

A JSON object representing an array of up to three objects representing the current user's selected topics for the last three epochs. Each object contains the following properties:

• configVersion
  • : A string identifying the algorithm (other than the model part) used to calculate the topic.
• modelVersion
  • : A string representing the model used to classify a string (such as a web page's hostname) into topic IDs.
• taxonomyVersion
  • : A string representing the taxonomy version used.
• topic
  • : A number representing the ID of the topic, which can be used by the browser to retrieve the topic from the taxonomy (see an example taxonomy of interests).
• version
  • : The configVersion, modelVersion, and taxonomyVersion, concatenated with colons (:) between each.

Examples

The exact property values may vary by browser implementation. An example header from Chrome might look as follows:

Sec-Browsing-Topics: [{configVersion: "chrome.1", modelVersion: "1", taxonomyVersion: "1", topic: 43, version: "chrome.1:1:1"}]

Specifications

This feature is not part of an official standard, although it is specified in the Topics API Unofficial Proposal Draft.

Browser compatibility

See also

• Topics API