Conversions API (CAPI)

What Is the Conversions API?

The Conversions API (CAPI) is Meta’s solution to the declining reliability of browser-based tracking. Instead of relying on the Meta Pixel to send events from the customer’s browser, CAPI sends event data directly from your server to Meta’s servers.

Think of it this way: the pixel is like putting a camera in the customer’s browser (which they can block). CAPI is like your store’s register sending a receipt directly to Meta (which cannot be blocked by the customer’s browser).

Why CAPI Exists

The Meta Pixel was the standard tracking method for years, but it has become increasingly unreliable:

• iOS 14+ privacy changes block much of the pixel’s cross-app tracking
• Ad blockers prevent the pixel from loading entirely for many users
• Browser cookie restrictions limit the pixel’s ability to identify returning visitors
• Intelligent Tracking Prevention (ITP) in Safari expires cookies quickly

CAPI addresses all of these issues because it does not run in the browser. The data goes server-to-server, completely bypassing the customer’s device.

How CAPI Works for Shopify

When a customer completes a purchase on your Shopify store:

1. Your server processes the order
2. The server collects event data (order value, products, customer info)
3. The server sends this data to Meta’s CAPI endpoint via an HTTP request
4. Meta matches the event to the original ad click using hashed customer identifiers (email, phone, etc.)
5. The conversion appears in your Meta Ads Manager

CAPI vs Pixel: Key Differences

Feature	Meta Pixel	Conversions API
Runs on	Customer’s browser	Your server
Blocked by ad blockers	Yes	No
Affected by iOS privacy	Yes	Partially (still needs match keys)
Cookie dependent	Yes	No
Data reliability	Declining	More reliable
Setup complexity	Easy (paste a snippet)	More technical

Best Practice: Use Both Together

Meta recommends running the pixel and CAPI simultaneously and enabling deduplication. The pixel still captures some events that CAPI might miss (like page views from anonymous browsers), while CAPI catches the conversions the pixel misses. Together, they provide the most complete picture.

Deduplication uses an event ID to ensure the same conversion is not counted twice when both the pixel and CAPI report it.

CAPI Limitations

CAPI is not perfect. It still requires customer match keys (like email or phone number) to connect server events back to Meta ad clicks. If a customer checks out as a guest without providing identifying information, the match rate drops. Typical match rates range from 60-85%.

CAPI in Detectly

Detectly includes built-in server-side tracking that sends purchase events to Meta via CAPI automatically. No manual API integration required. This ensures your Meta campaigns receive accurate conversion data while Detectly independently tracks attribution via UTM parameters for your own reporting. See our Meta CAPI setup guide for Shopify for details.