What is Privacy Sandbox?

March 18, 2022


5 min read

Many browsers have begun blocking or removing third-party cookies in recent years to protect privacy. However, this can adversely affect essential web functionality, such as advertising and fraud prevention, without effective alternatives. In order to make sure publishers and developers can provide advertising-funded content without compromising privacy, major technical innovations are needed on the web. Google announced in August 2019 it was taking measures to protect the privacy of website users within its Chrome browser — a move that is similar to Mozilla with its browser Firefox (Enhanced Tracking Protection) and Apple with Safari (Intelligent Tracking Protection).Thus, Privacy Sandbox, scheduled to be completed in 2023, is under construction. ‘’The Privacy Sandbox will lay new foundations for a safer, more sustainable, and more private web.’’ says Google on their dedicated website: https://privacysandbox.com/

What is the Google Chrome Privacy Sandbox?

As an alternative to third-party cookies, Google Chrome’s Privacy Sandbox is announced as a set of measures designed to allow personalized advertising on the web while maintaining the privacy of web users.

FLoC’s interest-based cohorts

Simply explained: All user data is sent to the Chrome web browser, where it is stored and processed, meaning that they remain on the user’s device. Google has been examining ways to make sure advertisers can continue targeting users when third-party cookies are finally removed. In order to enable targeting, FLoC (federated learning of cohorts) was created. Google describes it as enabling “interest-based advertising on the web” without revealing the identity of the user. By eliminating the need to track individual user activity, FLoC will create profiles based on groups of users or “cohorts”.

Overview of the Current Third Party Cookies World

Third-party cookies track users individually, identifying them as unique tokens. Users are not necessarily identified by the search giant, but they are treated as unique entities for advertising purposes only. So users are unaware of what third parties are doing with their data when they visit a website. Covert tracking methods of this kind received strong negative press coverage. So how is building a more private, open web is possible?

A Plan for Balancing Advertising and Privacy

Chrome says that browsers should allow websites to access limited information about users so that users can be categorized into a cohort but not identified personally. Additionally, Google plans to establish central identity service providers that can access limited user data via APIs and give details about their information passed on. (Bindra, 2021) At each step, only the information required to assign a user to an ad target group should be passed on.

The Privacy Sandbox Proposals

1.Restrict Excessive Tracking:

What fonts you have installed or the size of your screen is necessary for a website to work correctly. When websites collect too many of these kinds of data, they can be used to create a digital “fingerprint” which can be used for continuous cross-site tracking. Preventing this kind of data over-collection aims to introduce a limit on how much information a site can access about a visitor and helps manage this “privacy budget” effectively. (Introducing the Privacy Budget, 2020) As an example, sites must specify what kind of information they require from their browsers, and sites that access excessive amounts of information can be blocked.

2.Fight Spam:

By introducing trust tokens, the Privacy Sandbox helps websites combat fraud without tracking people. You can receive a trust token from a website based on your behavior on the site, such as logging into an account regularly. By using the token, other websites can verify that you are a real person because you are a cohort member of A or B, a cohort consisting of people who have taken similar actions on a site.

3.Ads Targeting:

FLoC: Google elaborates on this popular acronym that will soon replace the third-party cookies as follows: ‘’With FLoC, the browser uses on-device computation to place you in a “cohort”. This group is large enough — numbering in thousands — that individuals can’t be identified, but the members are similar enough that they would likely be interested in the same kind of content or ads. Your browser history doesn’t leave your browser or device, and it’s not shared with anyone.’’ (The Privacy Sandbox: Technology for a More Private Web, n.d.)

Turtledove: Turtledove abbreviation stands for Two Uncorrelated Requests, Then Locally-Executed Decision On Victory. As a part of the Privacy Sandbox initiative, Turtledove is built for advertisers to keep on retargeting campaigns as usual without alienating them with something completely different, but this time in a privacy-compliant manner.

Ads Based on Visits: As audiences move across the web, the sites of advertisers they’ve visited can inform the browser that they would like a chance to show ads and even within what budget in the future.

4.Ads Measurement:

Privacy Sandbox offers advertisers a variety of ways to continue measuring their ad campaigns while maintaining individuals’ anonymity. In the aggregation method, for example, data is only reported if it is sufficiently aggregated across browser users, using a server-side aggregation service. Aggregation involves various privacy mechanisms (like adding noise) so that the data can only be learned about groups, not individuals.

Controversies on Market Power

AdTech professionals have the impression, Google might put their interest first like they allegedly did in the past. (Davies, 2019) Google has internal advertising platforms and dedicated teams such as Google Ads and DV360, and the question is whether those teams will be able to reach more than the aggregated data that will be offered to advertisers and publishers.

U.S. state attorneys have also released an amended complaint to stop Google’s Privacy Sandbox initiative, accusing Google of laying the groundwork of unfair competition. (Amended Complaint against Google, n.d.)


Google’s goal is long-term to standardize the process so it can be reliably used as a web standard in all browsers. While Google is excitedly awaiting feedback and collaboration, it remains unclear for now what other browsers think of Privacy Sandbox.****


Introducing the Privacy Budget. (2020, December 15). [Video]. YouTube. https://www.youtube.com/watch?v=0STgfjSA6T8&ab_channel=GoogleChromeDevelopers

Bindra, C. (2021, January 25). Building a privacy-first future for web advertising. Google. Retrieved November 11, 2021, from https://blog.google/products/ads-commerce/2021-01-privacy-sandbox/

The Privacy Sandbox: Technology for a More Private Web. (n.d.). Privacysandbox.Com. Retrieved November 11, 2021, from https://privacysandbox.com/proposals/floc

Davies, J. (2019, May 14). ‘Google is the only winner’: Google’s anti-tracking moves could slow Amazon’s ad growth. Digiday. Retrieved November 11, 2021, from https://digiday.com/media/google-winner-googles-anti-tracking-moves-slow-amazons-ad-growth/

Amended Complaint against Google. (n.d.). Https://Www.Texasattorneygeneral.Gov/. Retrieved November 11, 2021, from https://texasattorneygeneral.gov/sites/default/files/images/admin/2021/Press/Redacted Amended Complaint FILED (002).pdf

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