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 how PrestaSignal records the sale where it actually happens: in your shop, not in the browser.
Client-side: at the mercy of the browser
A client-side pixel runs as JavaScript in your visitor’s browser, and every privacy layer the browser ships gets a vote: Safari deletes the cookies scripts set within days, iOS lets shoppers refuse tracking outright, and ad blockers simply refuse to load scripts from the domains on their filter lists. When any of them wins, the conversion never reaches Google or Meta — and you never even know it is missing.
Server-side: recorded where the sale happens
PrestaSignal splits the work in two. Everything the browser sends — page views, product views, carts, checkout steps — travels through a small connector on your own website address, so nothing on your page loads from a third-party domain. And the sale itself never depends on the browser at all: your shop’s back office reports each order and refund server to server, with personal data hashed before it leaves your shop.
Two versions of the same shopper
The gap between what the browser reports and what really happened is not small. Roughly 3 in 10 internet users run an ad blocker (GWI, 2025) — and when a browser blocks Google’s domains, those sales simply never appear in your reports. That is budget spent on customers your ad platforms were never told about.
Why the ad-blocker row: today’s filter lists target Google’s domains — with PrestaSignal, nothing on your page loads from them, and the sale is recorded by your back office either way.
Why the thank-you-page row: the sale is reported the moment your shop validates the order. A closed tab, a lost connection or a blocked script changes nothing — the order exists, so the sale is counted.
Why the Safari row: we set a proper server cookie on your own domain. Apple’s 7-day deletion applies to cookies set by JavaScript — not to it — so a returning Safari visitor is still recognised.
Sources:GWI, 2025 ·webkit.org/tracking-prevention.
Not two tools — one integrated design
You don’t choose between a pixel and a server, and there is no “mode” to configure. The browser side contributes the in-session detail it is good at; your back office contributes the sale itself; and a shared event ID — built from the order, so a reload can never double-count — tells each platform to keep exactly one copy of every purchase.
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 — and PrestaSignal forwards the visitor’s consent choices exactly as given, never rewritten. Personal data (email, phone, name, city) is SHA-256 hashed 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. The browser side keeps collecting the rich in-session signals it is good at — served from your own address instead of Google’s — and the server side adds the sale your back office reports. The two share an event ID, so you gain coverage without double-counting.
Does server-side tracking beat ad-blockers completely?+
No honest vendor promises that. What is true by design: today’s filter lists target Google’s domains, and PrestaSignal serves everything from yours — and the sale itself is recorded by your back office, which no browser extension can reach. Consent is respected either way; this is about not losing legitimate, consented sales to browser-side blocking.
How much conversion data am I actually losing today?+
It varies by audience and device mix — no verifiable industry average exists. What is measurable: roughly 3 in 10 internet users run an ad blocker (GWI, 2025), and Safari deletes script-set cookies after 7 days (Apple’s own WebKit policy). 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.