What's Server Side vs Client Side Tracking?

In digital marketing and analytics, tracking is how businesses measure what visitors do on their website, whether that’s making a purchase, filling out a form, or simply clicking a button. Traditionally, most tracking has been client-side, but the industry is rapidly moving towards server-side tracking.

Here’s what you need to know.

What is Client-Side Tracking?

Client-side tracking happens directly in the user’s browser. When someone lands on your website:

• A tracking script (like the Meta Pixel or Google Analytics snippet) runs inside the browser.

• It collects data such as page views, clicks, and conversions.

• That data is sent directly from the browser to the ad platform or analytics tool.

Advantages of client-side tracking:

• Easy to set up, just paste a script on your site.

• Immediate event data, with lots of detail (e.g. device type, browser, location).

• Works out-of-the-box with most ad networks.

Disadvantages:

• Vulnerable to ad blockers and browser restrictions (Safari, Firefox, iOS updates).

• Cookies may expire quickly or be blocked entirely.

• Less control over the data being sent.

• Event loss is common (some conversions may never be reported).

What is Server-Side Tracking?

Server-side tracking (what PixelFlow offers) moves the data collection from the user’s browser to your server.

• A lightweight script still runs on the website to detect events (like a- purchase).

• Instead of sending the data directly to Meta or Google, the event is sent to your server.

• Your server then processes, validates, and forwards the data to the ad or analytics platform.

Advantages of server-side tracking:

• More reliable – events are less likely to be blocked or lost.

• Extended attribution – you can keep conversion data longer, even after cookies expire.

• Greater control – you decide what data is passed along.

• Privacy-friendly – allows compliance with GDPR and consent requirements by filtering and anonymizing data.

• Improved ad performance – better data helps ad platforms optimize campaigns.

Disadvantages:

• More technical setup (usually requires server infrastructure or a tool like PixelFlow).

• Slight delay in event processing compared to client-side tracking.

• Some very granular data (like exact browser details) may be harder to capture.

Why the Shift to Server-Side?

The marketing industry is changing:

• Apple’s iOS 14 updates made client-side tracking less reliable.

• Browsers block third-party cookies by default.

• Privacy regulations (GDPR, CCPA) require businesses to handle user data more carefully.

Server-side tracking addresses these challenges by ensuring that valuable event data is still collected, while giving businesses control over privacy and compliance.

Which One Should You Use?

The truth is: both have their place.

• Client-side tracking is simple, fast to set up, and still useful for real-time interactions.

• Server-side tracking adds reliability, compliance, and deeper insights.

That’s why many businesses today use a hybrid approach: basic events fire client-side, but are also backed up by server-side tracking for accuracy. This is also exactly what we provide at PixelFlow - for example, you add both your Meta Pixel and Meta Conversion API and both are loaded on your website and automatically deduplicated.

How PixelFlow Helps

Tools like PixelFlow make server-side tracking accessible to everyone not just technical teams. Instead of setting up your own servers and APIs, you can:

• Add a simple script to your site.

• Define the events you want to track.

• Let PixelFlow handle the rest, securely forwarding your events to Meta’s Conversion API.

✅ In short:

• Client-side = easy but unreliable.

• Server-side = reliable, private, and future-proof.

The future of tracking is server-side and the sooner you start using it, the more accurate your data and ad performance will be.