Nothing replaced Chrome's Topics API. See how it worked, why it was retired, and what interest-based ad targeting falls back on today.
No new browser API replaced the Topics API. Chrome's on-device interest signal is being retired without a successor, and interest-based ad targeting has fallen back on older tools: third-party cookies that Chrome kept under user choice, contextual targeting, first-party and logged-in data, and — where those fail — fingerprinting. This guide explains how Topics worked while it shipped, why it went away, and what that means for your privacy.
Key Takeaways
- There is no successor. The Topics explainer repository now opens with a banner saying the API "is deprecated and planned for removal from Chrome."
- Topics was a browser-mediated signal: Chrome inferred coarse interests from your browsing on your own device and handed a few of them to ad scripts, instead of letting those scripts follow you with a cross-site ID.
- Targeting did not disappear. It moved back to cookies you can choose to keep, to the content of the page you are reading, and to what a site already knows about you when you are logged in.
- The privacy cost is real: a coarse, rate-limited, noised signal is gone, and the identifiers that remain are more precise — cookies and fingerprints.
- You can see what your own browser exposes with BrowserInsight's fingerprint check.
What the Topics API was
Topics was one of the Privacy Sandbox proposals meant to support interest-based advertising once third-party cookies went away. Interest-based advertising picks an ad from interests derived from the sites you visited in the past; contextual advertising uses only the page you are on right now. Topics aimed to keep the first without the cross-site ID that cookies provided. Chrome Platform Status records the API's ship entry, with Topics enabled by default starting in Chrome 115.
How it worked
According to the Topics explainer, the mechanism had a few moving parts:
- On-device classification. The browser mapped the hostnames you visited to topics from a public taxonomy. The initial design had roughly 350 topics, chosen to exclude sensitive categories.
- Weekly epochs. Each week, the browser computed your top five topics from local browsing information. That history stayed on your device.
- A small hand-off. A script calling
document.browsingTopics()received an array of up to three topics, one from each of the preceding three weeks, in random order. The same signal could travel in aSec-Browsing-Topicsrequest header. - Noise. There was a 5% chance that a random topic was returned instead of a real one, to give plausible deniability.
- Per-site variation. Each site saw only one of your top five topics for a given week, so two sites would see different topics for the same person.
- Caller filtering. A caller only received a topic if it had itself observed you visiting a site about that topic in the past three weeks, so Topics did not hand interests to parties that cookies would not have reached.
The design goal was to be less identifying than a cookie: coarse topics, a few per call, with deliberate noise. It was a compromise, not a way to make ad targeting private.
Why it was retired
The Topics repository notes that the API is deprecated and planned for removal, and the repository itself is being archived. The reasoning came in Google's October 17, 2025 announcement that retired several Privacy Sandbox technologies at once, citing low adoption and ecosystem feedback on their value. That announcement is covered in the "Rollout timeline — and the retirement" section of our Chrome IP Protection guide, which also lists the other APIs retired alongside Topics.
Two other factors made Topics a hard sell. It was a Chrome-only API: neither Firefox nor Safari implemented it, so advertisers could never rely on it across browsers. And once Chrome decided to keep third-party cookies, the main reason to adopt a weaker, cookie-free signal largely went away. We have not found a removal date in any source we can cite, so we do not give one.
What interest targeting uses now
"What replaced Topics?" has no single answer, because the replacement is a set of existing methods:
- Third-party cookies, by user choice. Chrome backed away from removing third-party cookies by default, so the cookie-based approach Topics was meant to replace is still available where users allow it. Browsers such as Safari and Firefox block many of them regardless.
- Contextual targeting. Ads are chosen from the page being read, with no history needed.
- First-party and logged-in data. If you are signed in, the site or its ad partners can use what they already know — purchases, searches, an email-derived ID.
- Identifiers that survive cookie clearing. Where cookies are blocked, trackers fall back to techniques such as bounce tracking, which plants first-party identifiers through redirects, and CNAME cloaking, which disguises a tracker as your own site's subdomain. Browsers counter these with measures like storage partitioning.
- Fingerprinting. A persistent visitor ID is recomputed from your browser and hardware traits on every visit, so there is nothing to delete.
How much each method is used varies by site and ad network, and we have no primary source for adoption figures, so we leave the numbers out.
What losing Topics means for privacy
Topics was imperfect, but it had properties the fallbacks lack. It exposed a small, coarse, noised slice of your interests, you could in principle inspect and clear it, and it was built around not creating a stable cross-site ID. Cookies, redirect-based IDs and fingerprints are far more precise, and the last two are hard to see or remove.
That shifts the practical question from "which interests does my browser reveal?" to "what identifies me when cookies are gone?" The second question has a measurable answer in your own browser.
Frequently Asked Questions
Is the Topics API still in Chrome?
It has been deprecated and is planned for removal, according to the explainer repository. Treat it as discontinued and do not build anything that depends on it.
Did Google replace Topics with another API?
No. No successor API was announced as a replacement; interest targeting relies on existing methods such as cookies, contextual signals and first-party data.
How do I check or turn off Topics in Chrome?
In Chrome versions that still include it, go to Settings → Privacy and security → Ad privacy → Ad topics. There you can see the topics Chrome has inferred, block individual ones, or switch the feature off entirely.
Does this mean third-party cookies are coming back?
Chrome kept third-party cookies under user choice rather than removing them by default, so they never fully left. Other browsers block many of them by default.
Can I still be tracked without Topics?
Yes. Trackers can use cookies, redirect-based identifiers and fingerprints. Run the fingerprint check to see which browser traits could identify you.
Conclusion
The Topics API was a short-lived attempt to give advertisers a coarse, browser-mediated interest signal in place of cross-site cookies. Chrome is retiring it without a successor, so targeting leans on cookies kept under user choice, page context, first-party data and, when those are blocked, identifiers that need no cookie at all. To see how identifiable your own browser is, open the fingerprint check.
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