Conversions API (CAPI)
The Conversions API is Meta's server-to-server method of reporting conversions, sending events from your server instead of relying on the browser pixel alone.
Why it matters
The pixel alone now misses a substantial share of conversions. Since Meta's optimisation learns from the events it receives, missing events do not just under-report performance - they actively make the algorithm worse at finding buyers.
What people get wrong
That sending events through the API means they are being counted. A CAPI event that arrives without enough matching information - no hashed email, no phone, no click id - often cannot be attributed to a person who saw the ad, so it is received and then effectively discarded. The setup reports success at every step: events show as received in Events Manager, the integration reads green, and the conversions still do not appear where you expect them. Check the event match quality score, not whether events are arriving.