Extends the Attribution Reporting API to support a mechanism for generating and sending reports in a way that reporting endpoints can only learn aggregate data, not any data associated with a particular click or user. This proposal allows a site to specify reports they want to aggregate within an isolated worklet environment. These reports can later be forwarded to a set of aggregation services which generate usable reports and can apply differentially private noise.


There are numerous web ad measurement use-cases which cannot be supported by the event-level reports provided in the existing Attribution Reporting API proposal[1]. By sending aggregated data, we can provide meaningful privacy protections while allowing for higher fidelity measurement of attribution-trigger data to be received at a faster rate alongside event-level reports.


Specification link

Specification being incubated in a Community Group

Status in Chromium


No active development

Consensus & Standardization

After a feature ships in Chrome, the values listed here are not guaranteed to be up to date.

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Last updated on 2021-07-09