What is client-side tracking?
Traditional pixel tracking runs in the visitor’s browser. When someone views a product, adds to cart, or purchases, the pixel sends an event to the ad platform. That worked until a few years ago. The world changed.
Why client-side tracking is failing
- Ad blockers. About 30 to 40% of desktop users run one. Tools like uBlock Origin block pixels from Meta, Google, and TikTok, not just ads.
- iOS 14.5 and later. App Tracking Transparency means most users decline. The Meta Pixel on iOS is largely broken.
- Third-party cookie deprecation. Chrome is phasing them out. Safari and Firefox already did. Without cookies, the pixel struggles to match events to ad clicks.
What is server-side tracking?
Server-side tracking, also called Conversions API (CAPI), works differently. Your server sends the event to the ad platform. A visitor purchases on Shopify, Shopify registers the order, your server sends the purchase to Meta CAPI, Google Enhanced Conversions, and TikTok Events API, regardless of ad blockers, iOS, or cookie settings.
Dual-dispatch: both paths
The most effective approach is dual-dispatch, sending events client-side via the pixel and server-side via CAPI. Platforms deduplicate on event_id. Layer Insights does this automatically. lf.js runs in the browser for speed and browser signals. The CAPI gateway runs server-side for reliability and advanced matching.
Is server-side tracking GDPR-compliant?
Yes, if implemented correctly. CAPI still requires consent for personal data. Layer Insights implements consent-aware dispatch. If a user does not consent, we send a stripped payload without PII. Google Consent Mode v2 is implemented in lf.js.