Conversions API

The Conversions API is a way for your own server to report events straight to Meta, instead of leaving that job entirely to the pixel sitting in someone's browser.

You set the pixel up properly, checked it was firing, and then you open Events Manager and the purchase count is lower than what your own back office says you actually sold. That gap is the browser quietly losing events before they ever reach Meta, and the Conversions API is the fix that skips the browser altogether. When a sale happens, your server already knows about it, so you have your server send that event directly to Meta over the internet, no browser in the middle to block it, slow it down, or drop it. Both roads end in the same dataset: the pixel road runs through the visitor's browser, the Conversions API road runs through your server, and Meta reads them together.

This matters because the browser road has been getting weaker every year while the server road holds steady. Ad blockers, privacy settings, and people declining tracking all eat into what the pixel can send, and none of that touches your server. Meta now pushes the Conversions API hard for exactly this reason, because a dataset fed from both sides simply sees more of your real sales than one fed from the browser alone, and more complete data is what lets the Sales objective actually find buyers instead of guessing from scraps.

Turning it on is where people create their own mess. The moment your server starts sending the same purchase the browser is already sending, Meta is receiving that one sale twice, and unless you set up deduplication so it can tell the two reports are the same event, your numbers inflate and your optimization learns from a lie. The Conversions API is also only as honest as what you feed it, so sending the wrong value or firing on the wrong action just moves a bad signal from the browser to the server.

Send from the server as well as the browser, but match the two so one sale never counts as two.