What is a Conversion API (CAPI)?
A Conversion API (CAPI) is a server-side tracking method that sends conversion events directly from your server to an ad platform's servers, bypassing browser-based tracking limitations like cookie blocking and ad blockers.
How It Works
Traditional conversion tracking relies on browser pixels — small pieces of JavaScript that fire when a user completes an action on your website. The pixel sends data from the user's browser to the ad platform. This worked well until browsers started blocking third-party cookies, ad blockers became widespread, and Apple introduced App Tracking Transparency.
Conversion APIs solve this by moving tracking to the server side. When a conversion happens on your website, your server sends the event data directly to the ad platform's API. Because this is a server-to-server connection, it is not affected by ad blockers, cookie restrictions, or browser privacy settings.
Meta was the first major platform to launch a Conversion API (2020), followed by Google (Enhanced Conversions), TikTok (Events API), and LinkedIn (Conversions API). Each implementation differs in detail but shares the same principle: server-side event transmission for more reliable conversion data. Most implementations work alongside browser pixels rather than replacing them, using deduplication to avoid counting the same event twice.
Why It Matters for Advertisers
Without a Conversion API, you are likely underreporting conversions by 10-30% depending on your audience and industry. This underreporting leads to poor optimization (the ad platform cannot optimize for conversions it cannot see), inaccurate ROAS calculations, and misguided budget decisions.
CAPI is especially important for iOS users, where App Tracking Transparency has significantly reduced pixel-based tracking effectiveness. Advertisers who implement CAPI typically see improved match rates, lower CPAs (because the algorithm gets better conversion signals), and more accurate attribution data.
How Ad Superpowers Helps
Ad Superpowers reads the conversion data that your platforms report, including data from both pixel and CAPI sources. When you ask "How many conversions did my Meta campaigns generate this week?" you get the full picture — including server-side events.
Our tools also help you diagnose tracking gaps. If your pixel and CAPI are reporting very different numbers, or if your conversion volume dropped suddenly, you can investigate by querying event-level data and comparing across sources. The cross-platform attribution reconciler skill is particularly useful for understanding how CAPI implementation affects your attribution accuracy.
Related Terms
Attribution Window
An attribution window (also called a lookback window or conversion window) is the time period after a user interacts with an ad during which a subsequent conversion can be attributed to that ad.
Return on Ad Spend (ROAS)
Return on Ad Spend (ROAS) is a marketing metric that measures the revenue earned for every unit of currency spent on advertising. A ROAS of 4x means you earn four dollars for every dollar spent.
Model Context Protocol (MCP)
Model Context Protocol (MCP) is an open standard created by Anthropic that lets AI assistants connect directly to external tools and data sources through a universal interface.
Learn More
See It in Action
Connect your ad accounts and let AI handle the analysis. Free to start — no credit card required.