Tracking & measurement
What is Conversions API (CAPI)?
The Conversions API (CAPI) is a Meta tool that sends conversion events — purchases, leads, add-to-carts — directly from your server to Meta, instead of relying on the browser-based pixel alone. On Meta it complements the pixel by recovering events that ad blockers, cookie restrictions and Apple's App Tracking Transparency (ATT) cause the browser to drop, giving Meta more complete data to optimise and measure on.
Example
A shopper buys with an ad blocker on, so the browser pixel never fires. Your server still sends that Purchase event through the Conversions API, and Meta — after deduplicating it against any pixel event by event ID — counts the sale. Advertisers who add CAPI commonly recover a meaningful share of conversions the pixel alone was missing post-iOS 14.
Why it matters
Since the iOS 14 / ATT privacy changes, the browser pixel misses more conversions than it used to, which starves Meta's optimisation and understates your ROAS. Server-side events via CAPI restore that signal, so the algorithm learns from more complete data and reported results line up better with real revenue — it has become close to essential for accurate conversion tracking rather than a nice-to-have.
How to use and improve it
Run CAPI alongside the pixel (not instead of it) and send a shared event ID from both so Meta can deduplicate — otherwise you double-count. Pass strong customer-matching parameters (hashed email, phone, IP, user agent) to lift event match quality, and verify everything in Events Manager. If you'd rather not build and maintain the server integration yourself, the Geniusko Gateway provides a server-side CAPI relay that forwards events to Meta with deduplication handled for you.
Frequently asked questions
What's the difference between the Meta Pixel and the Conversions API?
The pixel tracks events in the browser; the Conversions API sends them from your server. Browsers lose events to ad blockers and privacy settings, so running both together — with event deduplication — gives Meta the most complete data.
Do I still need the pixel if I use the Conversions API?
Yes. Meta recommends running both and deduplicating shared events. The pixel captures rich browser signals while CAPI recovers what the browser drops; together they're far stronger than either alone.
Is the Conversions API free?
Yes — like the pixel, CAPI is a free Meta tool and you only pay for the ads. The cost is the engineering work to send server-side events, which is why relays like the Geniusko Gateway exist to handle it for you.
What is event deduplication and why does it matter?
When both the pixel and CAPI report the same conversion, Meta uses a shared event ID to recognise them as one event and avoid counting it twice. Without deduplication your conversions and ROAS would be inflated.
Related
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