Full Answer

The end of third-party cookies did not create a tracking crisis — it revealed which businesses had built durable data infrastructure and which had been renting someone else's.

Server-side conversion APIs emerged as the primary tracking mechanism. Meta CAPI, Google Ads Enhanced Conversions, TikTok Events API, and the newer ChatGPT Ads Conversions API all accept server-to-server event data. These APIs receive purchase events, customer identifiers, and attribution signals directly from the store's server, completely bypassing browser restrictions. The data is richer than what cookies ever provided because server-side events carry verified transaction data — actual revenue, actual products, actual customer identifiers — rather than the inferred behavior that cookie-based tracking estimated.

First-party data became the attribution backbone. When a customer provides their email address at checkout, that identifier connects their journey across platforms through deterministic matching. Google's Enhanced Conversions hash the email and match it to the user's Google account. Meta CAPI does the same against Facebook profiles. This matching is more accurate than cookie-based attribution ever was, but it only works for identified users — anonymous browsing sessions remain unattributable.

Consent management matured from a compliance checkbox into a data strategy component. Stores using Advanced Consent Mode send cookieless pings to Google even when consent is denied, enabling behavioral modeling that recovers a portion of lost signal. The recovery is partial — typically 5-10% — but meaningful for stores in regions with high consent rejection rates.

The stores that adapted earliest now have 18 to 24 months of clean, server-side data in their warehouses. That historical depth compounds into competitive advantage through better cohort analysis, more accurate lifetime value predictions, and bidding algorithms trained on complete conversion data.