What Is Google’s Privacy Sandbox and How Can You Get Started? 

Google Chrome plans to fully phase out third-party cookies in 2024, and with 63% of the global market share, this signals a significant change in how our industry considers addressability in advertising.  

In an effort to preserve effective advertising while protecting consumer privacy, Google launched Privacy Sandbox, a series of alternative solutions to third-party cookies.   

Let’s take a look at what Privacy Sandbox entails and what media owners, buyers, and tech platforms need to do to prepare their addressability strategies for a privacy-centric future.  

What are the Privacy Sandbox APIs? 

Privacy Sandbox is an initiative launched by Google to address the evolving landscape of consumer privacy and data protection in the digital advertising ecosystem. Google has developed a set of privacy-safe APIs to replace third-party cookies, all with the goal of striking a balance between consumer privacy and the needs of marketers and publishers to deliver relevant, targeted ads. 

There are several Privacy Sandbox APIs for web that aim to prevent spam and fraud, enable relevant advertising, allow for ad measurement and attribution, and strengthen cross-site privacy boundaries. These are the three APIs related to ad targeting and measurement: 

  1. The Protected Audience APIThe Protected Audience API (PAAPI) is a remarketing solution that allows marketers to re-engage with their recent audiences and prospective customers. To maintain consumer privacy, Protected Audience uses anonymised and generalised audience groups—known as interest groups—and moves the ad auction off the webpage and into a secure browser environment. PAAPI was previously known as FLEDGE. 
  1. The Topics APIThe Topics API categorises web pages into nearly 500 interest topics without revealing consumer data, enabling marketers to deliver relevant ads while safeguarding privacy. (You can view the taxonomy here, or see the topics associated with your Chrome browser by visiting chrome://topics-internals.) The browser will infer a handful of interest-based categories to help serve relevant ads, which can then be used to optimise ad buying models and decisioning. Topics was previously known as Federated Learning of Cohorts (FLoC). 
  1. The Attribution Reporting API The Attribution Reporting API helps measure ad campaign effectiveness and enable data-driven advertising decisions. It uses encryption, time delays, and data aggregation and randomisation for measurement without revealing an individual’s data to marketers or third parties. 

Testing Privacy Sandbox 

The shift from third-party cookies to Privacy Sandbox will require a massive effort. There are tens of thousands, if not hundreds of thousands, of marketer and publisher websites that need to be updated with API calls to Privacy Sandbox.  

Publishers, buyers, and tech platforms are readying their businesses and tech stacks now, and Google has already kicked off testing with many ad tech providers. In Q1 2024, Google will disable third-party cookies on 1% of Chrome traffic to assess tech readiness. 

At Index, we’ve begun testing both the Protected Audience and Topics APIs to help our customers and partners prepare for a cookieless future. If you’re interested in testing these solutions with us, please contact us.  

We encourage publishers using Prebid to begin testing now, which requires: 

  • Updating to the latest version of Prebid.js (8.18 or higher) 
  • Enabling the fledgeForGPT module  
  • Enabling all ad units to use the fledgeForGPT module in your Prebid.js configuration  

DSPs should also begin testing as we send Protected Audience impressions, available Topics, and Chrome-facilitated testing labels in bid requests. Here’s a snapshot of integration requirements for testing, and you can see the complete list here:  

  • Topics will be available in the and[].segment objects.  
  • Testing labels will be available in the cdep field in the device.ext object.  
  • Protected Audience bid requests will include the ae = 1 field in the imp.ext object.  
  • Bid responses should include perBuyerSignals for Protected Audience in the igbid field in the response.ext object.  

Additional Privacy Sandbox resources 

Privacy Sandbox presents a drastic change to the way programmatic has been executed to date, and the solutions are complex. We believe in education and sharing our knowledge widely so that we can all work together to advance the industry.  

To that end, we’ve made a few resources available to the industry to help you understand and implement these APIs, and will continue to share our learnings.

  • Index Explains: What Is the Protected Audience API? – Learn more about the privacy measures PAAPI introduces and exactly how it works. 
  • Protected Audience Diagram – This Protected Audience diagram provides developers with an in-depth look at the complex and technical flow during a PAAPI auction, breaking down what’s happening behind the scenes of each step. We’ve contributed this resource to the IAB Tech Lab to make it available to the industry for further collaboration. 
  • Protected Audience Demo – Developers can use our Protected Audience demo, also donated to the IAB Tech Lab Open Source Initiative, for a practical example of how PAAPI works today via the Console tab of the Chrome Developer Tools. 

What to expect on Privacy Sandbox from Index

This is a sizable transformation for the industry, and as with any new solution, there are still questions and concerns about how exactly Privacy Sandbox will work in practice. Answers will only be learned through testing, and we’re committed to helping as many publishers, DSPs, and marketers to test as possible.  

Testing will unlock a better understanding of the APIs and spark more dialog across the industry about ideal timelines, necessary actions, optimal designs, and so on. We’ll continue to collaborate with and provide feedback to the industry bodies driving adoption—IAB Tech Lab, Prebid, and the UK Competition and Markets Authority (CMA)—as well as Google Chrome, to share what’s working and elevate any concerns. 

We’ll update you on our progress and learnings throughout, so be sure to check back or subscribe to get our latest updates.  

In the meantime, don’t hesitate to get in touch if you have any questions. This is a major change and will require everyone across the industry to adapt. Our team is here to help, share our resources, and provide training. 

Mike McNeeley

Mike McNeeley

Senior vice president, product

As a major technology leader in the programmatic space, Mike holds nearly 15 years of experience in the online advertising industry. As senior vice president of product, Mike leads Index’s product division—overseeing the company’s product roadmap and direction, user interfaces (UIs), reporting, and technical industry group involvement—unlocking addressable buying opportunities across all screens and ad formats. Prior to joining Index, Mike worked at several technology companies including AppNexus, Yahoo! Search Marketing, and Right Media. During his tenure at AppNexus, Mike was responsible for the team that created and launched Prebid and, as well as the strategy, pricing, go-to-market, and roadmap for its SSP product.

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