Also called: CAPI, Facebook Conversions API, Meta CAPI, server-side pixel
Deduplication is the part that goes wrong. Each event must carry the same event_name and event_id from both the browser and the server. Omit the event ID and Meta counts one purchase twice, doubling your reported conversions and corrupting the bidding signal you installed CAPI to improve.
CAPI improves event match quality by sending hashed customer information — email, phone, name, city, external ID — that the browser pixel often cannot access. Match quality directly affects how well Meta can attribute and optimise, and Meta scores it out of 10 in Events Manager.
All personal identifiers must be SHA-256 hashed and normalised before sending: lowercase, trimmed, phone numbers in E.164. Sending a raw email address is both a policy violation and a data-protection incident.
For advertisers of any real scale, CAPI is the difference between Meta seeing roughly half your conversions and seeing nearly all of them — and Meta bids against what it can see, not against what happened.
Yes. Meta recommends running both. The browser pixel supplies browser-side signals (fbp, fbc, user agent) that improve match quality, and the redundancy means one failing does not take all measurement with it.
By matching event_name plus event_id across the two sources within a 48-hour window. Both sides must generate and send the same event_id for the same user action — usually a UUID minted once per event and passed to both paths.
Meta scores match quality from 1 to 10. Above 6 is generally healthy; above 8 is strong. Scores are raised by sending more hashed identifiers per event — email plus phone plus external ID beats email alone.
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