Conversions API (CAPI)

Definition

The Conversions API (CAPI) is a server-side method of sending conversion data straight from a business's server to an ad platform like Meta or Google. Because it doesn't rely on the browser, it recovers conversions that browser-based pixels miss due to ad blockers, privacy settings, and cookie restrictions.

In depth

It sends conversion events the back way — server to server — instead of through the visitor's browser. A traditional tracking pixel fires in the browser, where ad blockers, privacy settings, and the disappearing third-party cookie can stop it cold. This method bypasses all that by reporting the event from your own server directly to the ad platform, so the conversion still gets counted even when the browser-side tag would have failed.

For a contractor, this is the difference between campaigns that look broken and campaigns that look as good as they actually are. Privacy changes have quietly erased a real chunk of browser-tracked conversions, which makes ad platforms under-report results and optimize poorly — so good ads get paused and budget gets misread. Restoring that lost signal gives the platform more complete first-party data to bid on and gives you honest numbers to make decisions from.

The misconception is that it replaces the pixel — it doesn't; the two work together, with deduplication so a single conversion isn't counted twice. Used alone, server-side tracking can miss browser context; used together, they cover each other's blind spots. WellBuilt runs this alongside the Meta Pixel (and Google's equivalent) with proper deduplication, so clients get the most complete, accurate conversion picture privacy rules still allow.

Worked example

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