The 5 things you should know about Google’s Privacy Sandbox

Mar 25, 2024

10 min read

February was a big month for Google’s Privacy Sandbox and the industry's perception of it. March and April will hopefully be the months where more testing will take place. Until now, the Privacy Sandbox has been sometimes perceived as the ultimate alternative solution that will save the industry from third-party cookies being removed from Chrome. In February the IAB Tech Lab published their findings after testing the Sandbox on use cases defined by the industry. The report is the first practical and realistic (maybe at times pessimistic) look into the Sandbox. 

Now, at Rayn, we’ve been staying very close to Google’s Privacy Sandbox and the news around it, as we see the potential benefits it can bring to the industry, but we’ve also found ways to create a bit more ease for advertisers and publishers to take advantage of it. 

Before we deep dive into IAB’s report and possibilities, here are the five things you absolutely need to know. 

1. Google’s Privacy Sandbox objective is not to replicate the efficacy of third-party cookies. Well, then what is it? According to Google: to enhance user privacy while supporting effective digital advertising in a world without cookies. 

2. The question on everyone's mind: is Chrome going to play a role in advertising? And even though it feels like an easy “Yes” to the outside world, Chrome has been adamant that they want to stay out of it. This disconnect happens because we use Chrome and Google interchangeably when that is not the case. Now Chrome wants to stay out of it, but it seems that they are facilitating the bid, defining the audiences, and are controlling several use cases. We’ll leave it up to you to determine what that means. 

3. The Privacy Sandbox requires significant time and resource investment from all sides of the ecosystem to set up and allow (once) familiar workflows to continue existing. It won’t be a simple plug-and-play solution and we as an industry will need to re-learn how this part of the ecosystem works as well as re-build around it.

4. As an advertiser wanting to reach consumers in Chrome, familiarising yourself with Google’s Sandbox is key. There are a few things you need to be prepared for: like how to target, the fact that you will probably bid against yourself, and more. To avoid some of these pitfalls, you could work with pre-registered interest groups (like the ones Rayn creates, combining multiple characteristics). 

5. As a publisher, even though you have less control over how your inventory is defined and broadcasted, there are a couple of things you can do to make your life easier like declaring topics, registering interest groups, and applying for related website sets. All of these will have an impact on your monetisation in a cookieless Chrome environment. 

If you still don’t know where to start, this is something we can help with at Rayn (give us a ). To name a few, we help register interest groups, allowing you to target more than just a singular attribute, we can create synthetic relevant data allowing you to preserve scale in a privacy-first environment, and our expertise and technology work beyond Chrome. Reach out to us here. 

Now if you’re still reading, you are one of those curious people who really want to understand your options. So let’s get into the nitty-gritty. 

The Privacy Sandbox is a new way of defining privacy in browsers or operating systems to allow for digital advertising once Chrome no longer supports 3rd party cookies at the end of 2024. The Privacy Sandbox is not merely a response to the deprecation of third-party cookies, but a paradigm shift that significantly influences the programmatic ecosystem. And if you haven’t yet, it’s about time you started thinking about how you’ll use it. 

IAB Tech Lab Report Findings

The IAB Tech Lab conducted a Privacy Sandbox analysis where more than 60 companies were involved in the project which lasted several months. Here are the main findings:

Basic Advertising Use Cases are limited

30 out of 46 advertising use cases defined by the IAB Tech Lab report are limited, impacted, or no longer possible within the Privacy Sandbox. According to the report, the programmatic ecosystem will face challenges in addressability, tracking, targeting, measurement, lookalike modeling, frequency capping, and interoperability. The Tech Lab also found exclusion targeting, the use of VAST tags, budget pacing, and second-price auctions impractical using the Chrome Privacy Sandbox APIs. 

Documentation is confusing

If you want to figure out any of the use cases available in the Privacy Sandbox, you have to take a look at the Sandbox Github repository,, and to figure out how to enable them. The IAB is asking for more complete documentation for a clearer understanding of sandboxes’ capabilities. The overall technical information shared by Google on the Privacy Sandbox has been seen as insufficient and lacking transparency.

Liability Issues

Until now it was clear that a DSP has a relationship with an SSP and the SSP has a relationship with the publisher. This relationship was governed by explicit contracts between the DSP and SSP covering matters such as sequential liability, discrepancy thresholds, and data rights. Now that the Privacy Sandbox bundles an ad server and an SSP into the Google Chrome browser, parties need to reevaluate their liabilities. “People need to ask themselves, ‘Who am I contracting with?’ and that’s just entirely unclear to the industry!”  according to IAB Tech Lab CEO, Anthony Katsur. 

The industry’s response is key

The consensus seems to be the industry isn’t ready yet. 

But the real question arising is: did we truly expect the industry to be ready for such a major change? We’re talking about the same industry that didn’t take privacy for real until major fines for GDPR violations were introduced. Look how long it took for us to believe that 3rd party cookies are going away and start preparing for it. 

To leave behind the industry’s 25-year-old practices is challenging and not without pain, but we think embracing Privacy-preserving technologies, including the Privacy Sandbox, and adapting to the new paradigm is essential. Waiting it out is not a viable option and the players that understand the new ecosystem first will be the ones that will advance in it.

So what are the implications for Publishers, then? 

Publishers will have to adapt operationally, create audience segments specific to Chrome, and adjust reporting and technology setups. They would have to learn how new technology works. Declaring topics, and registering interest groups becomes very important. Even something simple like registering for related website sets so that several domains can function in a first-party context. Transforming 5 different sites into one first party is a pretty good offering from Google in the privacy sandbox, but it’s not well known, so not a lot of publishers have taken the steps to make it happen. 

But in all fairness, Publishers didn’t know about this because the privacy sandbox processes don’t seem to be transparent for Publishers. The bottom line is that what Publishers have to do is highly operational and process-heavy, but they have to take it seriously because a large chunk of their revenue comes from this browser.  

The limitations on data access and the ensuing challenges with personalization may have an impact on publishers' monetization opportunities and make it more difficult to sell high-value ad space. Publishers might be forced to modify their business models and come up with new ways to monetize their content, such as partnering with other platforms, introducing new advertising technology, or diversifying revenue streams. 

Implications for Advertisers

On the other hand, advertisers face a paradigm shift in retargeting methods, moving from cookie-based strategies to aggregated reporting and attribution APIs. The significant market share of Chrome, approximately  64.38%, translates to a considerable user base of 400 million daily active users. Adapting to Chrome-specific strategies becomes imperative to protect revenue streams and maintain cost-effective outreach. The viability of the Privacy Sandbox for publishers and brands depends on industry-wide adoption. It introduces a different way of transacting, empowering first-party data owners but requiring a significant shift in industry practices and technology stacks. 

Restricting access to data makes it more difficult to target and personalize advertising. Measuring campaign performance and the efficient use of advertising budgets are hampered by the usage of aggregated data. Future costs for marketers could rise as a result of less accurate targeting and more competition for advertising space. This would require an adjustment of budgets and strategies and can be a major impediment, especially for advertisers with limited budgets.

Cookies were the bridge between everything media buying, measurement, and attribution related. Or at least they were perceived as such. The truth is we’ve lived in a world where cookies aren’t available for more than 40% of the inventory for years now. While there is still hope that there will be a 1-on-1 replacement of cookies without too much effort to preserve all use cases as they were, the reality is that it’s not the case. 

But with this change, there are opportunities arising as well. The keys lie in a combination of focus on first-party data strategies, combined with advanced probabilistic and synthetic data strategies. Let’s not negate the power of new technologies that are developed - like GenAI and advanced ML models. We live in a world where Marketing personas can be turned into Media personas, where advertising across channels can be streamlined, and where context is actually winning. 

There seems to be an overall consensus that publishers and advertisers can better navigate cookie deprecation by developing robust strategies around first-party data. Embracing the Privacy Sandbox and going through the steep learning curve sooner rather than later will make a difference. 

Google’s Response

Adapting to this new way of working requires a reengineering of systems, reporting, and an adjustment to a different status quo. Google’s solution is a departure from established practices. 

But that’s kind of the whole point, right? We’re here because we used cookies in a way they were never intended to be used. So what Google is responding to the IAB Tech Lab Report is the following: “The Privacy Sandbox APIs provide building blocks that support business goals while preserving privacy for people. They are not designed to offer 1:1 replacements for third-party cookies or cross-site identifiers. To deliver meaningful improvements to user privacy, it's not viable to recreate every marketing tactic as it exists today.“

Google is standing firm amidst a storm of criticism over its Privacy Sandbox project, boldly asserting that the majority of the desired functionalities are indeed achievable through its APIs. Victor Wong, Google’s senior director of project management says that over 90% of the analyzed use cases are within reach. While Google urges adaptation and innovation from ad tech companies, it's clear that navigating this new terrain won't be a walk in the park.

Take, for instance, the issue of lookalike modeling. The Tech Lab's report states that this feature isn't currently supported by the Privacy Sandbox, leaving a glaring gap in functionality. Google's response? Essentially, it's a DIY situation. If you want it, build it using the tools we've provided, such as the Private Aggregation API. In other words, Google's not handing out ready-made solutions on a silver platter, the ecosystem will have to roll up its sleeves and get to work. If you’re not sure where to start, and you need some help, we’re one Rayndrop away 

Google is welcoming collaboration with open arms and awaits additional IAB Tech Lab and broader ecosystem input on possible improvements. But Wong mentioned they will not budge on certain fronts. Requests to recreate cross-site tracking using the Privacy Sandbox APIs are met with a resounding no. They're drawing a line in the sand, determined to uphold their privacy principles. It's a stance that's sure to ruffle some feathers, especially among those who've grown accustomed to more invasive tracking methods.

So all of this in the name of Privacy…

All other browsers and operating systems have been using privacy as a unique selling point and limited more and more functionality to the point in which some consent management platforms can’t even function because they can’t remember its settings for long enough, all in the name of privacy, for consumers. So how is consumer privacy enhanced in the Privacy Sandbox?

Privacy Sandbox ensures transparency for users by decentralizing decision-making to the browser. Users have greater control over their data and online tracking, as personal data is not sent to numerous parties. The shift to browser-based ad auctions, such as in the Privacy-First Ad Auction (PAAPI), prevents the creation of extensive user profiles by moving the auction process to the client side. Even more than that, by allowing users to set up ad topics of interest and decide which sites display advertisements, the Privacy Sandbox enhances transparency for consumers. We could argue that users are now active participants in the decision-making process, a fundamental shift from the previous cookie-centric model.

Privacy Sandbox Trial. Chrome is exploring new features that allow sites to deliver the same browsing experience using less of your (consumer) data. Here is where you can make privacy settings based on your preferences. 

Is Cookie Deprecation being delayed… again?! 

And as if things weren’t complex enough as they were, the UK Competition and Markets Authority could delay Google’s timeline for the phase-out of the use of third-party cookies. While acknowledging Google's compliance with its commitments so far, the CMA highlights several areas of concern that need addressing before the complete removal of third-party cookies later this year. The CMA has specifically asked Google to:

Ensure that its Privacy Sandbox proposals do not reinforce Google's advertising products' market dominance.

Address design issues with other Privacy Sandbox tools, such as potential disadvantages for small ad tech firms with the Topics API alternative and governance of the Topics API taxonomy.

Clarify long-term governance arrangements for the Privacy Sandbox.

Provide assurances regarding the future development of Privacy Sandbox tools, including ongoing engagement with industry stakeholders.

The expectations for the Privacy Sandbox have been set very high and it seems that with the current version, these expectations haven’t been met. We will keep a close eye on the future improvements Google will bring to the sandbox and get prepared for a bumpy journey into the new world of advertising. 

If there is one thing to remember from this - Google’s Sandbox is not meant to replace third-party cookies, and we as an industry have an opportunity to develop and deploy Privacy-preserving strategies, that protect publisher revenue and increase the success of advertising efforts. There is more than one way to reach your goal. And if you want a head start we can help you out with that. Reach out to and make sure you’re one of the first who will be able to win in the new ecosystem.

Catch the first Rayndrops with us.

Catch the first Rayndrops with us.

Rayn believes data can be used differently, ethically, and successfully and we are driving this change Rayndrop by Rayndrop.

Rayn believes data can be used differently, ethically, and successfully and we are driving this change Rayndrop by Rayndrop.

kvk 89337220 / vat NL864951024B01

Danzigerkade 15 C (3rd floor), 1013 AP Amsterdam

kvk 89337220 / vat NL864951024B01

Danzigerkade 15 C (3rd floor), 1013 AP Amsterdam