Chrome 115 shipped with Topics API at general availability. Third-party cookies continue to function in Chrome with no deprecation date confirmed for 2023. These two facts exist simultaneously, and the cognitive dissonance this creates in the programmatic industry is contributing to a planning paralysis that is actively counterproductive.

The industry conversation has fragmented into two unproductive camps. Camp one: “Privacy Sandbox is live, the cookieless future is here, urgency is maximum.” Camp two: “Cookies still work, the deadline keeps moving, we’ll deal with it when we have to.” Both camps are wrong in the same way — they are treating cookie deprecation as a binary event when the actual transition is incremental, already underway in some environments, and best managed with a parallel measurement strategy that works regardless of when any specific deprecation date arrives.

Here is what is actually happening: Privacy Sandbox APIs are live and available. No one is required to use them. Cookies are available and functional. No one is required to use them either, in an environment where they are blocked (Safari, Firefox) or in an environment where a user’s specific Chrome privacy settings have blocked them. The industry is already operating in a partial-signal environment that the binary “cookies are dead/alive” framing completely misses.

The State of Topics API at GA: What You Actually Get

Topics API in Chrome 115 provides the API as a production feature across the global Chrome user base. The practical reach depends on how many publishers have implemented the Permissions-Policy: browsing-topics header to opt in to topic assignment and how many DSPs have integrated the document.browsingTopics() JavaScript call to read topics in bid contexts.

Publisher adoption as of GA launch is not complete. IAB Tech Lab’s Privacy Sandbox task force has been tracking implementation readiness across publishers and adtech vendors, and the honest characterization is that while major SSPs and some large publishers have Topics API integration in progress or complete, the long tail of open-web publishers is far from uniform adoption.

DSP integration varies. The Trade Desk has been among the most active Privacy Sandbox testers. Google’s own DV360 obviously has native integration. Other DSPs are at various stages of integration, with some having deployed Topics signal reading and others still in evaluation. The result is that Topics API-based buying in July 2023 is available but reaches a subset of inventory on a subset of publishers through a subset of DSPs — not the full programmatic universe.

This is expected and appropriate for a GA launch. It is not a reason to either overstate or dismiss the Topics API readiness.

The Parallel Running Strategy

The most operationally useful response to the current situation is running Privacy Sandbox APIs in parallel with cookie-based campaigns, rather than waiting for one to replace the other. The specific mechanics:

Run Topics-signal campaigns alongside your standard cookie-based campaigns on overlapping audiences. Target both campaigns with the same conversion goals and creative. Measure performance on: reach overlap (what proportion of Topics-reached users are also in the cookie-based audience?), CPM differential (what do Topics-based impressions cost versus cookie-based equivalents in similar inventory?), conversion rate comparison (controlling for audience composition differences), and incrementality (are Topics-based campaigns reaching genuinely incremental users not accessible via cookies?).

This parallel running generates measurement benchmarks now, while cookies are still fully functional and provide the control comparison. When cookie deprecation begins for a meaningful share of Chrome users, you will have real data on Topics API performance rather than needing to construct those benchmarks under deprecation pressure.

The parallel measurement approach also surfaces the specific campaign types and audience segments where Topics API substitution is most viable versus most problematic. Upper-funnel awareness campaigns targeting broad interest categories will likely show better Topics API substitutability than lower-funnel retargeting or behavioral-segment-dependent prospecting. Knowing which campaign types have viable Topics substitutes before deprecation allows you to prioritize remediation planning.

What to Track in Your DSP, SSP, and Analytics

The specific measurement metrics to establish baselines on now, while you still have cookie-based benchmarks to compare against:

In your DSP: impression-level reporting on Topics-tagged versus cookie-tagged impressions, bid win rates and CPMs segmented by signal type, and conversion rates by targeting signal source. Most major DSPs now offer Privacy Sandbox signal reporting alongside standard audience reporting.

In your SSP or publisher analytics: Topics API fill rates versus standard programmatic fill rates, CPM distribution for Topics-enabled versus standard impressions, and publisher opt-in coverage rates by supply source. Publishers who have opted into Topics API may report materially different fill and CPM characteristics than unenrolled supply.

In your measurement infrastructure (GA4, MTA, or MMM): segment conversion attribution by traffic source for Chrome-versus-Safari-versus-Firefox to understand your current cookie dependency by browser. Chrome conversion rates versus Safari conversion rates on the same campaigns are a direct measurement of the cookie contribution margin — the performance gap between browser environments where cookies work and where they don’t.

Google’s Privacy Sandbox testing resources provide specific guidance on how to instrument your campaigns for meaningful parallel measurement. The instrumentation work is non-trivial but worth doing now rather than retrofitting during an active deprecation period.

Don’t Wait for the Forcing Function

The specific behavioral trap here is waiting for Google to announce a firm deprecation date that creates enough urgency to force investment. Every previous deprecation extension has allowed this behavior to continue. But the urgency argument does not depend on the deprecation date — it depends on the measurement gap you already have in Safari and Firefox environments.

Firefox and Safari together represent meaningful browser market share — roughly 25-30% depending on your audience demographics. If your campaigns are not running attribution analysis that accounts for the population of users in non-Chrome browsers where third-party cookies are already blocked, you have a measurement blind spot that is affecting your optimization right now. The cookie deprecation date is the Chrome component of a problem that is already real in non-Chrome environments.

The investment in parallel measurement infrastructure, first-party data development, and Privacy Sandbox testing pays off in three ways simultaneously: it closes the measurement gap in current non-Chrome environments, it builds the benchmarks you will need for Chrome deprecation whenever it arrives, and it provides competitive measurement sophistication that advertisers who are still running cookie-only programs do not have.

FAQ

If third-party cookies still work in Chrome, why should I run Topics API campaigns now? Running Topics API campaigns alongside cookie-based campaigns now, while cookies are still functional, allows you to build performance benchmarks that show how Topics API performs relative to cookies. When Chrome deprecation begins for a portion of users, you will have real data on Topics API performance rather than needing to calibrate under deprecation conditions.

How does the Topics API situation in Chrome compare to the cookie-free environment in Safari and Firefox? Safari and Firefox have effectively blocked third-party cookies for several years. The current Chrome situation — Topics API available but cookies still functional — is a transition step toward the state that already exists in other browsers. Analyzing your campaign performance differential between Chrome and Safari/Firefox traffic now provides a cookie-dependency estimate that is relevant regardless of the specific Chrome deprecation timeline.

What Privacy Sandbox metrics should I be tracking in my DSP? Track Topics-signal impression volume as a percentage of total impressions, CPM comparison between Topics-enabled and standard cookie-based impressions, conversion rate for Topics-targeted audiences versus cookie-based comparable audiences, and reach overlap between Topics audiences and your existing cookie-based custom audiences.

Is Topics API sufficient to replace all of my current behavioral targeting use cases? No. Topics API covers broad interest-based targeting from 350 categories. It does not replicate retargeting (re-reaching previous site visitors), specific behavioral segment targeting based on site visit patterns, look-alike audience modeling, or conversion list exclusions. These use cases require separate Privacy Sandbox proposals (FLEDGE for interest groups, Attribution Reporting API for conversion measurement) or alternative identity solutions.