This API measures ad conversions (e.g. purchases) and attributes them to ad interactions without using cross-site persistent identifiers like third-party cookies. The API allows measurement through both event-level reports sent directly from the browser, and aggregatable reports which can be processed through a trusted service to create summary reports of attribution data. An earlier version of this API was in Origin Trial from Chrome 86 through Chrome 97 which only supported click-through
Currently, the web ad industry measures conversions via identifiers they can associate across sites. These identifiers tie information about which ads were clicked to information about activity on the advertiser's site (the conversion). This allows advertisers to measure ROI, and for the entire ads ecosystem to understand how well ads perform. Since the ads industry today uses common identifiers across advertiser and publisher sites to track conversions, these common identifiers can be used to enable other forms of cross-site tracking. This doesn’t have to be the case, though, especially in cases where identifiers like third party cookies are either unavailable or undesirable. A new API surface can be added to the web platform to satisfy this use-case without them, in a way that provides better privacy to users.
Explainers: https://github.com/WICG/conversion-measurement-api/blob/main/EVENT.md https://github.com/WICG/conversion-measurement-api/blob/main/AGGREGATE.md https://github.com/WICG/conversion-measurement-api/blob/main/AGGREGATION_SERVICE_TEE.md