Conversions API (CAPI)
Also known as: CAPI, Server-Side Tracking
The Conversions API sends conversion events to Meta directly from your server, supplementing the browser pixel for more complete and reliable tracking.
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What it actually means
The Conversions API, or CAPI, is Meta's server-to-server tracking method. Instead of relying solely on the browser-based pixel — which ad blockers, iOS privacy features, and cookie restrictions increasingly disrupt — CAPI sends conversion data from your own server or platform directly to Meta. This recovers events the pixel misses, improves attribution accuracy, and gives the optimization algorithm more complete data to work with. The best practice today is to run the pixel and CAPI together with event deduplication, so each conversion is counted once even when both channels report it. For accounts that have seen tracking degrade since iOS 14, CAPI is often the single biggest fix.
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A local business losing track of leads since Apple's privacy changes can recover much of that signal with CAPI, which reports conversions even when the browser pixel is blocked.
Official definition
Straight from the ad platform's own help pages:
- Meta Business Help Center — Best practices for Conversions API to help improve ad performance (undated page; read September 26, 2026)Run the Conversions API alongside the Meta Pixel, deduplicate the shared events, and aim for a 75% event coverage ratio of Conversions API to Meta Pixel events.
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Related terms
The Meta Pixel is a snippet of code on your website that tracks visitor actions and sends them back to Meta for measurement and ad optimization.
iOS 14's App Tracking Transparency requires apps to ask users for permission before tracking them, which sharply reduced the data Meta can use for ad targeting and measurement.
Attribution is the process of crediting conversions to the ads, clicks, or impressions that led to them, determining which marketing earned the result.
Event deduplication prevents Meta from double-counting a conversion that is reported by both the browser pixel and the Conversions API.
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