http header
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.
| Header type | [Request header](https://developer.mozilla.org/en-US/docs/Glossary/Request%20header) |
|---|---|
| [Forbidden request header](https://developer.mozilla.org/en-US/docs/Glossary/Forbidden%20request%20header) | Yes (Sec- prefix) |
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, andtaxonomyVersion, concatenated with colons (:) between each.
- : The
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.