Why your browser pixel keeps losing sales.
Client-side tracking was built for a more permissive web. Today the browser is a battleground of privacy controls — and your pixel is losing. Here is the honest comparison, and why moving tracking to the server changes the maths.
Client-side: at the mercy of the browser
A client-side pixel runs as JavaScript in your visitor’s browser. That means every privacy layer the browser ships gets a vote: Safari’s ITP caps how long cookies live, iOS prompts let users opt out of tracking entirely, and ad-blockers simply refuse to load the script. When any of them wins, the conversion never reaches Google or Meta — and you never even know it is missing.
Server-side: measured at the source
Server-side tracking records the event on your own server, where the sale actually happens, then sends it to the ad platforms through their official APIs. There is no browser script to block, no cookie to expire, no extension in the way. The conversion is captured first and forwarded cleanly — with personal data hashed before it ever leaves your server.
Two versions of the same shopper
The gap between what the browser reports and what really happened is not small. For many PrestaShop stores it is 30–50% of conversions — budget spent on customers your ad platforms were never told about.
It is not either/or
The strongest setup runs both: a browser tag for the rich, real-time signals it can still gather, and server-side for the conversions the browser would lose — deduplicated with a shared event ID so nothing is counted twice. PrestaSignal gives you that hybrid out of the box.
Client vs server — answered.
Is server-side tracking allowed under GDPR?+
Server-side tracking is a method, not a loophole. It must still respect consent. PrestaSignal is built to honour consent state and hashes personal data (email, phone, name, city) with SHA-256 on your server before anything is transmitted — so you can be both accurate and compliant.
Will I lose the data my current pixel collects?+
No. In hybrid mode the browser tag keeps collecting what it can, and server-side adds back the conversions it would have lost. The two are deduplicated, so you gain coverage without double-counting.
Does server-side tracking beat ad-blockers completely?+
For conversion data, effectively yes — the event is recorded on your server, not in a script an ad-blocker can refuse to load. Consent is still respected; this is about not losing legitimate, consented conversions to browser-side blocking.
How much conversion data am I actually losing today?+
It varies by audience and device mix, but 30–50% is common once iOS, Safari ITP and ad-blockers are accounted for. A free tracking teardown will measure your specific gap.
Find out which conversions you’re losing.
A free teardown shows your real client-vs-server gap, measured on your own store.