Observe-Browsing-Topics

Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

Non-standard: This feature is non-standard and is not on a standards track. Do not use it on production sites facing the Web: it will not work for every user. There may also be large incompatibilities between implementations and the behavior may change in the future.

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

The HTTP Observe-Browsing-Topics response header is used to mark topics of interest inferred from a calling site's URL (i.e., the site where the ad tech <iframe> is embedded) as observed in the response to a request generated by a feature that enables the Topics API. The browser will subsequently use those topics to calculate top topics for the current user for future epochs.

See Using the Topics API for more details.

Header type Response header
Forbidden header name No

Syntax

http
Observe-Browsing-Topics: ?1

Directives

?1

A character sequence declaring that topics of interest inferred from a calling site's URL (i.e. the site where the ad tech <iframe> is embedded) are marked as observed. The browser will subsequently use those topics to calculate topics of interest for a user for future epochs.

Specifications

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

Browser compatibility

BCD tables only load in the browser

See also