Chrome Privacy Sandbox June 2026: The State of Alternative Attribution

Google has spent years developing a replacement for third-party cookies. The Privacy Sandbox is its answer: a collection of APIs that aim to deliver the advertising functionality that cookies enabled while eliminating the cross-site tracking that made cookies a privacy nightmare. As of June 2026, the Privacy Sandbox is the largest change to web privacy in a decade. But it is not a privacy improvement — it is a restructuring of the tracking ecosystem that centralizes advertising data under one company's control. What the Privacy Sandbox Replaces Third-party cookies allowed any website to drop a tracking identifier that worked across every other website. Advertisers used this to track users across the web, build interest profiles, and measure ad effectiveness. The model was simple, decentralized, and invasive. The Privacy Sandbox replaces this with a set of APIs that perform similar functions but through different mechanisms: Topics API replaces interest-based advertising. Instead of tracking individual users across sites, it observes browsing behavior on-device, assigns interest categories, and shares the top categories with sites that request them. Attribution Reporting API replaces conversion measurement. Instead of a cookie that persists across sites, it reports ad impressions and conversions through a secure reporting pipeline controlled by Chrome. Protected Audiences replaces retargeting. Instead of a persistent cookie identifying users for specific advertisers, it allows ad auctions to run on-device without exposing individual user identities. Each API performs the function of a cookie. None of them actually reduce tracking — they change who controls the tracking data. The Topics API The Topics API is the most visible component. It works by observing which websites you visit, mapping them to one of 470 predefined interest categories, and sharing your top 3 categories with any site that requests them. The process is: Chrome observes your browsing on a list of known website categories The browser assigns interest scores based on visit frequency Once per week, the top 5 topics are selected Sites can request your top 3 topics and use them for ad targeting Topics data is stored locally and is not transmitted to Google's servers directly Critics point out that Google — which operates the largest ad network — has visibility into browsing behavior through its own services (Search, YouTube, Maps, Gmail) that other advertisers do not have. The Topics API gives Google a structural advantage: it can observe interest signals across all Chrome users while third-party advertisers must rely on the limited topic categories Chrome provides. Attribution Reporting The Attribution Reporting API measures ad effectiveness without persisting cross-site identifiers. When a user sees an ad and later converts (makes a purchase, signs up), the API attributes the conversion to the ad impression. The system works through a combination of event-level reports and summary reports: Event-level reports pair a limited ad impression data with conversion data Summary reports aggregate conversions over time to prevent individual identification Reports are delivered through Google's reporting servers The privacy protection is that individual conversion events are not linkable to individual users. But the aggregation happens through Google-controlled infrastructure, meaning Google has access to the aggregate data that other ad platforms do not. Regulatory Response The EU has examined whether the Privacy Sandbox constitutes anti-competitive behavior. The concern is that by controlling the replacement for cookies, Google controls the new advertising infrastructure in a way that disadvantages competitors. In the UK, the CMA (Competition and Markets Authority) has been monitoring Chrome's cookie deprecation since 2022. As of June 2026, the CMA has not determined whether the Privacy Sandbox satisfies competition requirements. In the US, the FTC has not taken formal action against the Privacy Sandbox, but the agency has expressed concern about Google's dominance in both browser market share and advertising infrastructure. What Users Can Do The practical options: Switch browsers. Firefox, Brave, and Safari do not implement the Privacy Sandbox. If you use Firefox or Brave, you are not affected by Topics API tracking. Disable the Privacy Sandbox. In Chrome, go to Settings > Privacy and Security > Tracking Protection and disable the Privacy Sandbox APIs. Use browser extensions. Extensions like Privacy Badger and uBlock Origin can block Privacy Sandbox scripts, though Google has worked to make this difficult. Use the tools on this site. Our Browser Fingerprint Checker and DoNotTrack Check tools show what signals your browser is transmitting. The Privacy Sandbox is not a privacy improvement. It is a restructuring of the ad tracking ecosystem that happens to replace cookies with a system that benefits the company that controls Chrome. The only meaningful privacy choice is to use a browser that does not participate.