Effectively use the Attribution Reporting API for ad measurement


Historically, ad-tech providers have used third-party cookies (3PC) as a mechanism for conversion measurement, and for attributing conversions to ad interactions. Conversion measurement provides critical ad performance data to advertisers, and helps optimize auction-based bidding strategies.

Currently, the online advertising ecosystem is pivoting towards improved ways to protect user privacy. Chrome’s Attribution Reporting API (ARA), a part of the larger Privacy Sandbox initiative, offers an alternative for measurement after the third-party cookie deprecation in 2024. Ad-tech providers, including Google’s ads platforms, should consider adopting the ARA to maintain high-quality conversion measurement and support the pivot toward user privacy protection.

Google Ads has made significant investments to use the ARA more effectively and to help advertisers achieve more accurate measurement. We encourage other ad-tech providers to integrate with the ARA, configure the integration to retrieve the data they need, and process the ARA's output to help maintain accurate measurement after the planned third-party cookie deprecation in 2024.

Goals of the ARA

The ARA has two goals:

  • Protect users’ cross-site and cross-app identities from ad-tech providers, advertisers, publishers and other entities by using differential privacy techniques, such as aggregation, or adding an element of noise to the data.
  • Provide useful measurement information to ad-tech providers, advertisers, and publishers.

The ARA represents a change to both the format and granularity of conversion data available to ad-tech providers. As a result, ad-tech providers must change their current measurement protocols in order to start leveraging the ARA.

A glimpse into our approach

Ad-tech providers who participate in the Privacy Sandbox initiative receive data from the ARA in two forms: event-level reports and aggregate summary reports. This way, two independent views of the same underlying data are available. We encourage ad-tech providers to configure the reporting settings in the API to optimize for better measurement accuracy without 3PC, as well as improve how these two types of reports can be post-processed and used together.

There are many possible ways to utilize the ARA reports. The methodology that works for an ad-tech provider will ultimately depend on its conversion data and measurement requirements. Google Ads has found that leveraging both report types can help the industry benefit from the strengths of each report.

Google Ads leverages both event types to produce a more complete, ad event-level log. We are committed to sharing our process and engaging with the ecosystem to help our partners and the broader industry transition into a future without third-party cookies.

For more details on how we’re implementing the Attribution Reporting API, please refer to our detailed technical guide.