Client-side pixels only across four platforms — coverage had fallen to 38%

The situation

An Australian supplement brand had been running ads across Meta, Google, TikTok, and Snap for 3 years. All four platforms used client-side pixels only. A tracking audit commissioned before a large Q4 spend push revealed that actual event coverage — real purchases reaching ad platforms vs Shopify orders — was 38%.

The problem

iOS 14 ATT had reduced browser-based pixel coverage over time. The Australian supplement market skews female, 25-45, heavily iOS. ATT opt-out rate in this demographic: ~72%. Client-side pixels were capturing only the 28% of Android users and ATT opt-in iOS users. All four platforms were optimizing on a non-representative 38% sample of actual buyers — the 62% who were iOS and privacy-conscious were completely invisible.

What we did

1. Built GTM Server-Side container on Google Cloud Run — single server endpoint receiving all client events
2. Configured server-side tags for all 4 platforms: Meta CAPI, Google Analytics 4 MP, TikTok Events API, Snap CAPI
3. Implemented platform-specific deduplication (event_id) for each platform
4. Passed enriched customer data (hashed email + phone) from Shopify order data for improved match rates
5. Measured post-implementation coverage: 89% vs 38% — a 2.3x improvement in signal quality

Why it worked

A full-stack server-side implementation is the definitive solution to iOS 14 signal loss. By routing events through your own server before sending to ad platforms, you bypass browser restrictions entirely. The real efficiency comes from managing all 4 platforms from a single GTM Server-Side container — one implementation, four simultaneous beneficiaries.