In short
A Conversions API sends conversion events from your own servers straight to an ad platform, instead of relying on a browser pixel that cookies, ad blockers, and short iOS cookie lifetimes increasingly break. Meta, Snap, TikTok, Pinterest, LinkedIn, X, and Reddit each run one; Google’s equivalents are Enhanced Conversions and the Data Manager API. Your server sends each event with hashed identifiers such as email and phone, the platform matches those hashes to its logged-in users, attributes the conversion, and feeds its bidding models. A production-grade setup deduplicates the server event against the pixel with a shared event ID, hashes at source, carries consent with every call, and reports higher match quality than the pixel alone. The platform then sees conversions it would otherwise miss, so both optimization and attribution improve. Datahash Signals runs this server-to-server path across every major platform from a single integration.
Why do Conversions APIs exist?
Browsers block third-party tracking, ad blockers strip pixels, and iOS limits cookie lifetimes. Platforms lose sight of conversions, so they built server-side paths that do not depend on the browser.
How does a Conversions API work?
Your server (or a platform like Datahash Signals) sends the event with hashed identifiers. The platform matches the hashes against its logged-in users, attributes the conversion, and feeds its optimization models.
What does a strong CAPI setup look like?
Deduped against the pixel with a shared event ID, hashed at source, consent-aware, and delivering measurably higher match quality than pixel alone.
How does a Conversions API work in practice?
KFC measured 5% additional purchases when CAPI ran alongside the Meta pixel, because the server path recovered conversions the browser had dropped. The figure and the quote sit on the KFC case study, attributed to the person who said it.
Reference: Meta for Developers, Conversions API