Conversions API (CAPI)

CAPI exists because browser-based tracking keeps losing ground. Ad blockers stop the pixel script, Safari deletes its cookies early, and Apple's App Tracking Transparency prompt cut off a large share of iOS signal. A server-to-server connection bypasses all of that: the event is generated where the order actually happens, in your shop backend or server-side tag manager, and arrives at Meta regardless of what the visitor's browser allows. Each event carries match keys such as hashed email, hashed phone number, the _fbp and fbc identifiers, IP address and user agent, which Meta uses to link the event to an account. Events Manager grades this as an event match quality score per event.

There are three common ways to implement CAPI. Platform integrations like the native Shopify connection are the fastest route and fine for standard shops. A server-side Google Tag Manager container gives you full control over what is sent and lets you serve Meta, Google and other endpoints from one stream, which is the setup most growing advertisers end up with. A direct API integration built by developers offers maximum flexibility for custom backends and offline events such as CRM-qualified leads. In every variant the decisive detail is deduplication: browser and server send the same event with the same event_id, and Meta keeps only one.

A conversion happens, for example a purchase. The pixel fires the Purchase event from the browser with an event_id; your server sends the same event with the same event_id through CAPI, enriched with hashed customer data the browser event may lack. Meta receives both, recognises the duplicate, discards one copy and keeps the version with the better match keys. The surviving event then feeds attribution, reporting and delivery optimisation exactly like a pixel event. If the browser event never arrives because of an ad blocker, the server event simply stands on its own and the conversion is still counted.

Incomplete conversion data hurts twice: your reported ROAS looks worse than reality, and Meta's delivery system optimises on a biased sample of your buyers. Restoring the missing share of events, which is typically largest in iOS and Safari heavy audiences, improves both at once. CAPI is also the only practical way to send offline and downstream events, such as a lead that later becomes a paying customer, back into campaign optimisation. One thing CAPI does not do: it does not remove the DSGVO consent requirement, it only changes where the data is sent from and gives you control over what is included.