Conversion API

Data & Tracking

Also: CAPI · Server-Side Tracking · Meta CAPI

What it isServer-to-server tracking that sends conversion data directly from your server to ad platforms

Why it mattersRecovers conversion data lost to browser tracking restrictions and ad blockers

Who needs itAny business running paid advertising that relies on pixel-based conversion tracking

Quick definition

A Conversion API (CAPI) sends conversion events directly from your server to an ad platform (Meta, TikTok, Google) bypassing browser-based tracking limitations caused by ad blockers, iOS privacy restrictions and cookie policies.

Where it shows up in the data

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Browser-side vs server-side tracking

Browser-side tracking (pixels) fires from the user's browser, where it can be blocked. Server-side tracking fires from your server directly to the platform, bypassing browser restrictions.

Deduplication

When you run both pixel and CAPI simultaneously, ad platforms need deduplication logic to avoid counting the same event twice. This is typically handled via event_id matching.

Event match quality

How well your server-sent events can be matched to real users in the ad platform. High-quality events include email, phone, name and location for better matching.

iOS 14+ impact

Apple's App Tracking Transparency (ATT) framework severely reduced the effectiveness of pixel tracking on iOS devices. CAPI helps recover some of this lost data.

What it actually means

Traditional ad pixel tracking relies on JavaScript running in the user's browser. When users have ad blockers, privacy browsers or iOS privacy settings enabled, this tracking fires incompletely or not at all. The result is systematic underreporting of conversions in your ad platform, which distorts ROAS, CAC and bidding signals.

Conversion APIs send the same event data directly from your server to the ad platform's API, before any browser-level filtering can occur. The data still requires user matching (hashed email, phone number) to attribute to specific users in the platform, but it bypasses the browser entirely.

The impact on campaign performance is significant. Ad platform algorithms use conversion data to optimise delivery toward users most likely to convert. When that data is incomplete, the algorithm can't optimise effectively. Better conversion data = better-performing campaigns.

If your pixel is your only source of conversion truth, you're making campaign decisions on 60-70% of the actual data.

How it shows up

Event match quality score in Meta Events Manager, number of conversions attributed via CAPI vs pixel, deduplication rate, gap between platform-reported conversions and actual order/lead data.

The Australian context

Australian iOS device penetration is among the highest in the world. This means the impact of iOS privacy restrictions on pixel tracking is proportionally larger in Australia than in markets with lower iPhone share. Australian e-commerce advertisers on Meta are particularly affected and benefit most from CAPI implementation.

Where people get this wrong

Implementing CAPI without deduplication logicRunning both pixel and CAPI without event_id deduplication causes double-counting of conversions. This makes ROAS look inflated and sends wrong signals to the algorithm.

Implementing CAPI but not sending customer data for matchingCAPI events with no customer data (email, phone) have low event match quality and can't be attributed to users in the ad platform. The data goes in but doesn't help.

Treating CAPI as a replacement for the pixelCAPI is a complement to pixel tracking, not a replacement. You want both for redundancy and the broadest data capture possible, with deduplication handling the overlap.

Common questions

What is Meta CAPI?

Meta's Conversions API (formerly Facebook CAPI) is a server-side API that lets you send web events, app events and offline events directly from your server to Meta. It works alongside the Meta Pixel to improve conversion tracking accuracy by capturing events that the pixel misses.

Do I need a developer to implement CAPI?

It depends on your platform. Shopify, WooCommerce and many other e-commerce platforms have native CAPI integrations that can be enabled without code. Custom websites require developer implementation. Meta also offers a manual setup via the Events Manager.

Does CAPI work for Google Ads too?

Google has its own server-side solution called Enhanced Conversions, which works similarly — sending hashed first-party customer data alongside conversions to improve attribution. The concept is the same: server-to-platform rather than browser-to-platform.

Will CAPI improve my Meta ad performance?

Potentially yes, if you're currently losing conversion data to browser tracking restrictions. Better conversion data improves the Meta algorithm's ability to find buyers. Most advertisers with significant iOS traffic see improved ROAS after proper CAPI implementation.

Keep exploring

About New Rebellion

New Rebellion is a marketing intelligence consultancy. We build tools, score Australian businesses on how their marketing actually performs, and publish Debrief every day. This dictionary is part of how we work in the open.

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