Privacy Sandbox in 2021: Testing a more private web

January 25th, 2021

A year ago we announced our intention to phase out third-party cookies and replace them with new browser features that are fundamentally more private. Since then, we’ve been working closely with the broader web community, including W3C, to design and implement new privacy-preserving technology, while also preserving the vitality and sustainability of the open web.

Today more than 30 different proposals have been offered by Chrome and others, including many that we believe, are key to rendering third-party cookies obsolete. Early test results are also looking promising (see below)!

We are excited to continue testing this foundational tech with the active involvement of ecosystem partners and industry forums – all to move the web forward, together. What follows are key updates since our announcements last January and October.

Early results, and new proposals ready for testing

Five different Privacy Sandbox proposals are available for testing now – or will be very soon – in key areas like fraud detection, the tailoring of content, first-party treatment of a company’s owned and related domains, ads measurement, and a private-by-default way to request browser info. In fact, early testing of the Federated Learning of Cohorts (FloC) algorithm shows that new privacy-preserving ad solutions can be similarly effective to cookie-based approaches. This is great news for users, publishers, and advertisers – all of whom are critical for the future of the web – so we’re excited to carry this work forward.

Another important area of focus is user-facing controls. In particular, it’s clear that people will want to tune whether the content is tailored to them (or not) – in addition to keeping their private info private. With the Chrome 90 release in April, we’ll be releasing the first controls for the Privacy Sandbox (first, a simple on/off), and we plan to expand on these controls in future Chrome releases, as more proposals reach the origin trial stage, and we receive more feedback from end-users and industry. You can find a full update on all trials on our blog.

Involvement across the ecosystem

It’s great to see companies like Salesforce, White Ops, and Yahoo! JAPAN, starting (or preparing) to test initial solutions like Trust Tokens, First Party Sets, and Conversion Measurement. In fact, all developers have access to public Chrome experiments, and the latest guidance can be found on, so please do test and share feedback. This type of engagement helps ensure that the various APIs work as expected in real-world scenarios, so the more ecosystem participation, the better!

Building better. Together.

One of the things that makes the web so great is that it’s by and for all of us; this is a special quality amongst today’s platforms, and is definitely worth celebrating! It also creates complexity and trade-offs that we have to manage thoughtfully – and collectively – as we introduce new technology. That’s why we continue to engage in industry forums like the W3C and are in active discussions with independent authorities –  including privacy regulators and the UK’s Competition and Markets Authority – to help identify and shape the best approach for online privacy, and the industry and world as a whole.

So here’s to the users, and coders, and advertisers, and content creators (and so many others) who’ve made, and continue to make the platform what it is today. And here’s to coming together, in service of a more private web.

Posted by Justin Schuh – Director, Chrome Engineering