How CAPI actually works
The Conversions API moves conversion reporting off the browser and onto your infrastructure. When a purchase or lead happens, your server sends the event straight to the platform through a direct connection, carrying the same information a pixel would plus server-side context like hashed customer data for matching. Because the report never travels through the visitor's browser, none of the things that block a pixel, ad blockers, tracking prevention, a failed script load, can stop it. It is the same events, sent by a channel the browser cannot interfere with.
Why CAPI became necessary
For years the browser pixel was enough. Then Safari's tracking prevention, ubiquitous ad blockers, and consent requirements started stripping a large and growing share of pixel events, and platforms lost visibility of real conversions. That loss is not just under-reporting; it degrades optimisation, because the bidding model can only learn from events it receives. CAPI restores the missing signal by sending events server-side, which is why platforms now actively push it and why iClick treats it as baseline infrastructure rather than an optional upgrade.
Deduplication: pixel and CAPI without double-counting
Running the pixel and CAPI together raises an obvious worry: won't the same purchase get counted twice? It won't, if events are deduplicated. Each event carries a shared identifier, an event ID and matching parameters, so the platform recognises the browser-sent and server-sent versions as the same conversion and keeps only one. Get the event IDs wrong and you do double-count, which inflates conversions and misleads bidding. Correct deduplication is the difference between CAPI fixing your measurement and CAPI corrupting it.
What a good CAPI setup requires
CAPI is more involved than pasting a pixel. It needs a server-side integration, often through a platform's native connection, a tag manager server container, or a partner integration, plus correct event deduplication and good customer-data matching to attribute conversions accurately. Done well it recovers conversions and improves match quality; done carelessly it double-counts or sends malformed events. iClick sets CAPI up alongside a verified pixel and reconciles the combined result against the backend, because server-side tracking is only an improvement if the data it adds is correct.
