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FLEDGE origin trial and AdSense

On, or after, September 24, 2022, AdSense will begin testing FLEDGE as part of Chrome's origin trial. The FLEDGE origin trial will run for a limited time and on a small percentage of overall traffic.

Because auctions are run in the browser with FLEDGE, AdSense publisher controls can apply differently to interest group ads. This article describes those differences.

What is the Privacy Sandbox and FLEDGE?

The Privacy Sandbox provides web technologies that preserve people’s privacy online and give companies and developers the tools to build thriving digital businesses, which keeps the web open and accessible to everyone.

One of the Privacy Sandbox proposals being tested in Chrome is called FLEDGE (First Locally-Executed Decision over Groups). FLEDGE provides new privacy-preserving ways to support remarketing and custom audience solutions so advertisers can re-engage with site visitors.

With FLEDGE, the browser stores advertiser-defined user interest groups and hosts on-device auctions to show ads. Similar to how interest groups work today, FLEDGE will help marketers do things like showcase different product categories, appeal to visitors who didn’t convert, and re-engage visitors who abandoned shopping carts. Unlike today, however, companies will not be able to track individual users across the web via third-party cookies.

How AdSense serves ads with FLEDGE

When a user visits an advertiser’s website, the website (or an ad tech provider embedded on the website) can ask the user’s browser to associate the user with a specific interest group. The user’s browser then periodically fetches information about potential ads which could be shown to the user for each interest group, including information from advertisers.

Later, when a publisher wants to serve an ad to the user, an ad request is sent to AdSense. This request does not contain any information about FLEDGE interest groups. Once third-party cookies are deprecated, the request won't contain any third-party cookie data.

AdSense then runs a server-side auction to select the best non-interest group ad. Note that publisher controls apply as usual during the server-side auction. Following the server-side auction, AdSense returns the best non-interest group ad to the browser as well as information about publisher controls to apply in the on-device auction.

Finally, the browser runs an on-device auction between all interest group ad candidates and the best non-interest group ad. The winning ad is then rendered.

Blocking controls can behave differently with FLEDGE

The behavior of blocking controls described here is for testing during the origin trial only and on the small percentage of traffic (<1%) included in the origin trial. The behavior may change in the future as we learn from testing and gather feedback from publishers.

During initial testing, the blocking control for animated display ads will not apply, meaning animated ads may serve via FLEDGE even if you’ve enabled the blocking control.

Moreover, because FLEDGE auctions are run in the browser, AdSense blocking controls apply during the on-device auction in order to prevent potentially sensitive publisher data from being exposed in the browser. Specifically, for sensitive category blocks and restricted category opt-ins if at least one sensitive or restricted category is not allowed to serve, we won’t allow ads from any sensitive or restrictive category to serve. For example, if a publisher has blocked dating ads, then no ads from sensitive or restricted categories will be allowed to serve.

All other blocking controls, regulatory restrictions and consent controls will continue to be honored in FLEDGE.

Opting out of the FLEDGE origin trial

If you want to opt out of Chrome's FLEDGE origin trial, use Chrome’s Permissions-Policy:

  • Set Permissions-Policy:run-ad-auction=() in the HTTP response header during the origin trial, which prevents anyone (including AdSense) from running FLEDGE auctions on your site.
  • You can also set Permissions-Policy:join-ad-interest-group=() to prevent advertisers from adding users to interest groups on your site.
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