For five years, Privacy Sandbox was pitched as the thing that would replace the third-party cookie, and the Topics API was its poster child for ad targeting. Should you care about them yet? The short, slightly funny answer: no, because Google shut the whole thing down in 2025.

What actually happened

Two decisions ended the story. In April 2025 Google confirmed it would keep third-party cookies in Chrome instead of phasing them out. Then in October 2025 it announced it was retiring the Privacy Sandbox APIs entirely.

Topics, Protected Audience, and Attribution Reporting are being deprecated in Chrome and slated for removal through 2026. The UK's competition regulator, which had policed the whole effort, closed its investigation once Google was no longer killing cookies.

What the Topics API even was

Topics was Chrome's attempt to do interest-based advertising without cross-site tracking. The browser would assign each user a handful of coarse interest topics from their recent browsing, and sites could read those instead of following the user around the web.

It was a reasonable idea on paper. In practice, adoption was thin and advertisers never really trusted a black box the browser controlled.

Why it died

A few forces lined up against it:

  • Low adoption, because nobody rebuilds their stack for an API with an uncertain future.
  • Regulatory pressure, with antitrust scrutiny over Google controlling both the browser and the ad market.
  • Google's own choice to keep cookies, which removed the deadline that would have forced anyone to switch.

Once the cookie deadline vanished, the reason to adopt Topics vanished with it.

What to care about instead

The energy people were told to spend on Privacy Sandbox is better spent on things that are actually load-bearing:

  • First-party data, collected with consent, which you own regardless of browser politics.
  • Server-side tracking and clean consent, for durable measurement.
  • MMM and incrementality testing, which don't depend on any browser API.

Should you care about Privacy Sandbox and the Topics API yet? No, and now you never will, because Google retired them. The years you spent not rebuilding around them were well spent, so put that effort into first-party data and real measurement, the parts no browser can cancel.

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