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Attribution Reporting API

The Attribution Reporting API supports measurement of clicks and views with event-level and aggregate reports.

This repository hosts multiple technical explainers that specify various features of the API. This document offers an overview of the API and its explainers.

Get started

This repository hosts detailed technical explainers. Before diving into these, check out this introductory article. If you're looking to experiment with the API, head over to this guide.

All developer resources for this API are listed on


This API is being incubated and developed in the open. Here are ways to participate:

  • 🗓 Join the bi-weekly meetings (every second week). In these calls, participants discuss API design proposals and how the API could support various measurement use cases. You can add topics to the next meeting's agenda at any time. Everyone is welcome to join these discussions⏤only make sure to join the WICG.

If you have implementation questions, for example about your origin trial in Chrome, see how to get support.


The Attribution Reporting API makes it possible to measure when an ad click or view leads to a conversion on an advertiser site, such as a sale or a sign-up. The API doesn't rely on third-party cookies or mechanisms that can be used to identify individual users across sites.

The API enables two types of attribution reports:

  • Event-level reports associate a particular event on the ad side (a click, view or touch) with coarse conversion data. To preserve user privacy, conversion-side data is coarse, and reports are noised and are not sent immediately. The number of conversions is also limited.
  • Aggregatable reports provide a mechanism for rich metadata to be reported in aggregate, to better support use-cases such as campaign-level performance reporting or conversion values.

These two report types can be used simultaneously. They're complementary.

API features (proposals)

🕙 Last updated: Jan 2023

All the features below are proposals under incubation. This list evolves over time.

Event-level reports (clicks and views)

Attribute cross-site click-through or view-through conversions with reports at a per-event level.

See details in the Explainer.

Implementation status: Available in Chrome as an origin trial

Aggregatable reports (clicks and views)

Attribution reports for aggregated conversions (both clicks and views). Complements the event-level reports.

See details in the Explainer.

Implementation status: Available in Chrome as an origin trial

App-to-web (clicks and views)

Attribution reports for web conversions for ad clicks (touches) or views that occurred within an Android app.

See details in the web explainer and Android explainer.

Implementation status: Expected in Chrome and Android for origin trial in Q2 2023.

External documentation

Chrome developer resources for the Aggregation Reporting API are available on

Android has documentation on