Conversion API (CAPI)
Conversion API is the server-to-server measurement protocol used by Meta, Google, TikTok, and others to send conversion events directly from your server to the ad platform — bypassing browser-side tracking constraints.
In context
Conversion API is the modern alternative (and now complement) to browser pixel tracking, which loses 20–40% of events to cookie restrictions, ad blockers, ITP/ETP, and iOS privacy. Implementing CAPI restores most of that lost signal, materially improving ad-platform optimisation accuracy and downstream ROAS. Implementation is engineering-medium: capture events server-side, hash PII, send to the platform's CAPI endpoint, deduplicate against the browser pixel using event IDs.
A Canadian D2C brand implemented Meta CAPI alongside its existing pixel and saw the platform's reported conversion volume rise ~30% — same actual conversions, just with more of them being measured.
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