Membership Required
You need to sign in and have a Premium subscription to access this content.
- 01 51% of internet traffic is bots, 37% is malicious bots (Imperva 2025 Bad Bot Report, 2024 data)
- 02 Ad blockers completely block GA4, GTM, Facebook Pixel, and TikTok Pixel, causing 15-30% data loss
- 03 Safari ITP caps JS-created cookies to 7 days, and to 24 hours for ad click traffic
- 04 Server-side tracking (sGTM, Cloudflare Zaraz) or self-hosted analytics (Umami) can compensate for most of these losses
- 05 Cumulative loss estimate: out of 10,000 server-side visitors, GA4 may only see 3,000-5,000
+ Why can't client-side tracking collect complete data?
Client-side tracking collects data by executing JavaScript in the browser. Bot traffic, ad blockers, browser privacy policies (ITP, ETP), and page abandonment before JS loads break this mechanism at four different points. Each source alone can cause 10-50% data loss, and these sources stack on top of each other.
+ How can I collect data from ad blocker users?
Proxy-based solutions like Cloudflare Zaraz route tracking requests through your own domain, bypassing ad blockers. Server-side GTM provides partial protection. Self-hosted analytics tools like Umami don't appear on blocker lists when running on your own domain.
+ How does Safari ITP affect GA4 data?
Safari ITP deletes JS-created cookies (including GA4's _ga cookie) after 7 days of no user interaction. Safari users who don't return within 7 days are counted as new users on every visit. For visitors from ad clicks, this window drops to 24 hours.
+ Does server-side tracking completely solve these problems?
Server-side tracking provides advantages in bot filtering, ad blocker bypass, and cookie management, but it's not a silver bullet. Consent requirements still apply server-side. Additionally, ITP has started capping CNAME-cloaked cookies to 7 days as well.