Conversion & attribution
What is Conversions API (CAPI)?
A server-to-server channel (Meta CAPI, TikTok Events API) that sends conversion events directly to an ad platform, alongside or instead of the browser pixel.
Definition
A Conversions API sends conversion events from a server directly to an ad platform — Meta’s Conversions API (CAPI) and TikTok’s Events API are the main examples — rather than relying solely on a browser pixel.
Because it doesn’t run in the browser, it isn’t blocked by ad blockers, ITP, or a user closing the tab. Paired with the pixel and a shared event ID for deduplication, it recovers events the browser would lose.
Why it matters for agencies
CAPI is now table stakes for Meta and TikTok performance: pixel-only setups under-report and feed worse optimization signal. But it’s also the source of the most common modern tracking bug — double counting when deduplication isn’t configured.
Agencies are expected to run pixel + CAPI with correct dedup. "We added CAPI" without the shared event ID makes the numbers worse, not better.
Conversions API in Phloz
Phloz models the Conversions API endpoint as a node and the audit engine specifically flags a Meta Pixel with no CAPI counterpart — and the starter map deliberately seeds CAPI so a new client’s setup doesn’t immediately trip the pixel-without-CAPI rule.
Frequently asked questions
- Do I still need the pixel if I have CAPI?
- Yes — run both. The pixel captures browser context CAPI can’t, CAPI captures events the browser drops, and a shared event ID deduplicates the overlap. Pixel-or-CAPI is the wrong framing; it’s pixel-and-CAPI.
- What causes CAPI double counting?
- Sending the same conversion from both the pixel and CAPI without a matching `event_id` on each. The platform can only deduplicate if both copies carry the same ID — miss that and every purchase counts twice.
Related terms
Other tracking-infrastructure concepts agencies run into alongside this one.
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