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Demystifying Privacy Sandbox - what advertisers need to know now


By Jenni Baker, Senior Editor

January 11, 2024 | 12 min read

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With one of the most significant changes for the advertising industry coming this year, the time for testing cookieless solutions is now. Hanne Tuomisto-Inch helps demystify the Privacy Sandbox to explore what marketers should be doing next.

How advertisers can get ahead on protecting privacy in a future without third-party cookies

How advertisers can get ahead on protecting privacy in a future without third-party cookies

The countdown to third-party cookie deprecation is on. Chrome started deprecating cookies for an initial 1% of users earlier this month, to facilitate real-world testing and will begin phasing out support for third-party cookies in the second half of 2024, subject to final approval from the Competition and Markets Authority (CMA).

While marketers know that finding a solution to replace third-party cookies is critical to future success, some research suggests that marketers are still working to hone their individual solutions.

There’s no question that change brings challenges; especially when it comes to transitioning from technologies that advertisers have relied on for decades, like third-party cookies. Improving privacy on the internet requires the right building blocks to continue to reach audiences and measure advertising in the future in a way that is optimized for both business outcomes and user privacy.

A strategic approach

One could argue that the shift in technology required to prepare for a future without third-party cookies has been something that adtech companies and publishers have been much closer to. But preparing for the deprecation of third-party cookies is not just about the plumbing, it’s strategic.

“Often marketers and advertisers can be at arm’s length from the technology that powers their marketing,” explains Hanne Tuomisto-Inch, director, Privacy Sandbox at Google. “And because we’re seeing lots of different avenues being explored, it could be making the various solutions and options available more complex and, to an extent, fragmented - so it can be quite confusing for advertisers.”

It’s important for advertisers to be able to lean on agencies and partners to help cut through the noise, but it’s just as important to have an in-house understanding of the technologies and allocate budget for testing. Advertisers don’t need to manage and run the technologies, but to succeed, they should leverage the ecosystem to help align those strategies with the vision for the business.

“Marketing leaders need to be building that big picture in their head and aligning it to their vision,” says Tuomisto-Inch. “In order to understand how to respond to the changes in the ecosystem, you need to understand your business objectives first and have clarity of the direction you’re going. Consumer expectations of privacy are increasing, regulation is getting tighter, so you need to have a clear vision of how to respond and set clear expectations for the vendors you’re working with.”

While some ‘privacy-preserving’ solutions sound similar - they’re not. Tuomisto-Inch points out there are significant differences in terms of privacy protection, specifically for users: “You need to scratch under the surface. It’s not enough to just have user controls for transparency or a code of conduct, you need to have privacy built into the technology itself as well. You need to dig deeper into cookieless solutions sets, in line with your vision for privacy and how you’re going to meet user expectations. There are lots of solutions out there that don’t do that.”

Demystifying the Privacy Sandbox

The goal of Privacy Sandbox, working in collaboration with industry partners since 2019, has been to build alternative technologies to third-party cookies that improve privacy across the web for users while ensuring businesses have the tools they need to succeed.

“The future of the open web is dependent on user trust so we are absolutely focused on building new technologies that allow people all over the world to continue accessing free content across the web, while trusting that their privacy and choices are respected,” explains Tuomisto-Inch. “Fundamental to this is that people shouldn’t have to accept being tracked in order to get the benefits.”

The goal has always been to enable a robust, ad supported ecosystem that provides privacy improvements for users, is successful for developers and publishers, and ensures advertisers don’t have to track individual consumers to get the performance benefits of digital advertising; where relevant ads can be shown without sharing the user’s identity with third-parties, while continuing to enhance the safety and privacy of users.

It’s for this reason that the Privacy Sandbox initiative has been prioritizing and leveraging privacy enhancing technologies. Aggregation, noising, private auctions, on-device processing, and others are built into the relevance and measurement APIs to help hide the user’s identity and minimize data collection.

A collaborative effort

The Privacy Sandbox initiative is grounded in four guiding principles:

  1. Privacy and access to information should be universal
  2. Viable alternatives are a prerequisite for real, durable privacy to avoid more covert forms of tracking that users aren’t aware of and can’t control
  3. Solutions need to provide technical protections for privacy
  4. They must be built in the open, in collaboration with the industry.

That’s why the Privacy Sandbox team has been working with browsers, adtech companies, advertisers, agencies, publishers, and developers to participate in both the development and testing of these new technologies. “We need to make sure that this is an ecosystem-wide initiative to ensure that it improves privacy for users while providing utility for the industry,” says Tuomisto-Inch.

“The only way that this is successful is if we make sure that the feedback is incorporated from the start and to make sure the technologies themselves are effective for the industry. An open, healthy dialogue and collective discussion - including criticism - has been fundamental to this initiative and essential to advancing progress.”

Providing the building blocks

But it’s important to note that the Privacy Sandbox Ad Measurement and Relevance APIs are not solutions that can just be applied right out of the box. Rather these technologies will work best when combined with adtech companies’ own range of solutions to meet the needs of their customers.

“It’s not a standalone adtech solution for advertisers and publishers,” explains Tuomisto-Inch. “Privacy Sandbox for the web provides the building blocks that other providers can then incorporate into their own products and solutions, alongside other signals that they will be using. For example, contextual or first-party data, as well as the advanced machine learning and AI they are using will help ensure all of this works well for their customers.”

She also points out that Google Ads have the same access to the capabilities of the Privacy Sandbox APIs at the same time as the rest of the industry, including businesses and other ad tech platforms.

What to do next?

Privacy Sandbox reached a key milestone in summer last year, where the Ad Relevance and Measurement technologies were fully ready for testing and adoption, meaning that advertising providers and developers could start scaling the use of these new technologies within their products and services. The latest development on January 4 with the deprecation of 1% of third-party cookies will now enable further real world testing.

“We’re now entering a critical period when adtech companies can integrate the new technologies into their products and services, as building blocks they can use to get ready for the transition away from third-party cookies,” explains Tuomisto-Inch. “At the same time, we have been rolling out new user controls that allow people to manage how their data is used.”

This means that users can tailor their experience on Chrome for example by customizing what Topics they are interested in, and which relevance and measurement APIs they want enabled, with clear explanations of how the technologies work and simple controls to manage them.

A checklist for advertisers

Now is a vital time for advertisers to take steps to get involved, working with their adtech and agencies to start adopting these technologies. Starting now will provide a longer runway to prepare, to learn and to optimize integrations. Here’s a checklist of steps to follow:

  1. Set a clear vision of the strategic benefits of marketing that respects user privacy, and be clear on the expectations of your vendors
  2. Speak to your agency about adopting more private ad solutions and allocating budget to test
  3. Speak to your adtech providers to understand their preparations and how they will operate when third-party cookies start to be phased out in the second half of 2024. How are they incorporating Privacy Sandbox technologies into future solutions? And, ask how you can get involved in tests.
  4. Think about the critical user journeys: don’t forget the infrastructure that powers your websites and understand and update areas of your sites that rely on third-party cookies. Development work may be required from a practical perspective around things like social and video embeds and social channels to ensure they will continue to function in the future.

“While we strive to build alignment across the industry, we’ll continue to move forward,” Tuomisto-Inch concludes. “The history of technology has shown that progress can’t always wait for consensus. The scaled testing enabled by the general availability of the technologies, as well as testing on a portion of traffic without third-party cookies, will help us all better understand the effectiveness of the Privacy Sandbox solutions as we move closer to a future without third-party cookies”.

Follow the links to see which adtech companies are testing and their contact details for FLEDGE (Protected Audience), Topics and Attribution Reporting. To learn more about Privacy Sandbox, visit

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