Eighteen months without CAPI — 71% of trial signups never reached Meta

The situation

A UK FinTech app had been running Meta campaigns targeting young professionals for 18 months post-iOS 14. Their CPL had doubled and their media buyer couldn't understand why audiences kept underperforming. The app was on iOS — their entire user base was iOS.

The problem

The Meta pixel on the web landing page was browser-based with no CAPI. The app itself had no Meta SDK or CAPI app events. iOS users who saw a Meta ad, clicked through to the web signup, and completed a trial start — all of that signal was lost due to ATT. Meta was optimizing on the 29% of users who had tracking enabled, generating audiences that didn't represent the actual converting demographic.

What we did

1. Implemented Meta Conversions API via server-side endpoint triggered on trial account creation in the backend database
2. Passed enriched signals: hashed email, hashed phone number, client IP, user agent, and fbc from URL parameter
3. Implemented event deduplication between pixel and CAPI using a shared trial_id as event_id
4. Launched new Advantage+ campaign with fresh learning phase — let Meta rebuild audience model with 71% more signal

Why it worked

iOS apps face a double hit: ATT opt-outs remove web pixel signal AND app SDK signal simultaneously. For FinTech apps where the user base is disproportionately iOS-heavy and privacy-conscious, this can wipe out 70-80% of conversion signal. Server-side CAPI from the backend completely bypasses the browser and app — it's a direct server call that sends the conversion signal regardless of what the user's device is doing.