Client Side vs Server Side Tracking

Client Side vs Server Side Tracking

May 12, 2022

By: Sander Kah

6 min. reading time

What is Server Side Tracking?

Server side tracking means that the events that take place on your website are measured through the server. This is in contrast to what most websites do through an on-page tracking pixel.

What is an event?

An event is an occurrence on a website. Many events take place on websites, for example, a visitor viewing a product page, adding a product to his shopping cart, or placing an order on the website; all these occurrences are events.

On most websites, these events are measured by means of a tracking pixel on the website and passed on to external tools such as Google Analytics, Facebook, E-mail marketing tools or other analytical tools.

Because these events are sent to external tools, these tools can use the data to make analyses and optimize campaigns. For example, you could create a campaign for people who have added a product to their cart but have not yet purchased it. Since these people are already pretty close to a purchase, the chances of them converting (making a purchase) are much higher than, say, someone who has never been to the website. So the quality of this data is very important and that's what we will be looking into in this blog.

In this article we compare the difference between Client Side and Server Side tracking in other words: Who passes the data to an external tool like Google Analytics for example?

There are 2 options: the computer of the user (client side) or the server of the webshop (server side).

Server side vs client side tracking

What is Server Side?

Server side means that the above mentioned events are forwarded from the server where the shop is running on as opposed to client side.

What is client side?

With Client side tracking, the user's computer sends the visitor data directly to an external tool. Client side tracking has a number of disadvantages which we will highlight below.

What are the problems of Client Side tracking?

Adblockers ensure that client side events are not forwarded

More and more users are installing so-called ad-blockers to prevent their data from being shared with websites. Many ad-blockers block the forwarding of visitor data.

Pixel measurement on website success page (client side)

Also, in order to measure conversions, for example, a pixel on the relevant (success) page must be loaded by the user. So if a user quits after the payment process, leaves his payment app, and does not return to the success page of the website, the conversion will not be passed on even though it took place.

The above ensures that the number of events that actually take place differs from the number of events that are measured via client side tracking.

Marketing automation depends on good data

Marketing tools are increasingly using automation, in which campaigns are automatically bid up or down based on the results of the campaign.

Think for example of Google Smart Shopping but also in Facebook or Instagram marketing there is usually bidding on a certain conversion (event) on which the campaign is optimized.

These conversions are the events that are measured, some examples are:

  • Purchase
  • Add to cart
  • Product view
  • Page View

This means that the measurement of these events is becoming increasingly important and the success of your marketing campaigns largely depends on it.

The more accurate the data is that you put in, the better the results of the campaign will be.

How does Server Side Analytics Tracking work?

In the case of Server Side Tracking the events are sent from the server of the website to the various analytical and marketing tools at the moment an event occurs (e.g. the order is paid). Because this happens on the server, things like ad-blockers and the failure of a visitor to return to a successful page do not affect the number of measured events.

The event is sent when the item is added to the shopping cart or the order in the webshop is paid instead of depending on a pixel on the website.

What are the results of Server Side Traking vs. Client Side Tracking?

Below you will find a comparison of Google Analytics server side tracking versus client side tracking. To do this comparison, we set up 2 Google analytics properties on a site of one of our clients. The data of one property is measured via the pixel (client side) and the data of the other property is measured via the server of the website (server side). We are comparing the results of April side by side so we are looking at the same data over the same period on the same website.

E-commerce overview Google Analytics comparison

First we are going to look at the overall E-commerce view in Google Analytics, this is an overview of all purchases measured through analytics.

In the screenshots below you can see a comparison between client side and server side tracking over a month.

Client-Side Tracking E-commerce Overview

Client Side Google Analytics eCommerce Overview

Server Side Tracking E-commerce Overview

Server Side Analytics April eCommerce Overview

In the table below you can see the differences explained in absolute values and percentage:

Client SideServer SideDifference
Revenue€ 72.539€ 94.91430,8%

Here you can already see significant differences in both the number of conversions and the total revenue measured.

To assign a conversion to a campaign, Google Adwords works with a so-called Google Click ID, this is a string that is added to the url of an ad, which measures whether a click on an ad leads to a conversion. Google assigns visitors and conversions to a certain campaign.

In Google Analytics (if you have linked your Google Ads account) you will find a report under Acquisition > Google Ads > Campaigns that shows you which campaigns have yielded conversions.

Client Side Tracking Campaign Overview

Client side analytics april google ads campaign overview

Server Side Tracking Campaign Overview

Server side analytics april google ads campaign overview

In the table below you can see the differences explained in absolute values and percentage:

Client SideServer SideDifference
Revenue€ 47.166€ 67.72543,6%

As you can see, here the differences are even greater. So this means that if you are using Google Ads you are missing out on a huge amount of data here if you are not using Server Side Tracking.

What does Server Side Events do to your results?

For this client, we forwarded the conversions from Google Analytics to Google Ads on March 24th, which meant that the campaigns started receiving more data. As of the following week, we have seen a 40% increase in purchases and a 67% increase in sales.

The only adjustment we made during this period was turning on SSE. Below is a screenshot of the results from March 25 to 31, compared to the previous period.

Server Side Tracking Results Comparison

As you can see, the number of purchases increased by 40% and the revenue of this webshop increased by a whopping 67%.

How can I use Server Side Events from Afosto?

Currently we offer Server Side Tracking for both Google Analytics and Facebook Business (Facebook and Instagram advertising).

In order to use SSE you need to create an account on Afosto via this link.

You also need to have an Afosto webshop and a Google Analytics or Facebook Business account. You can create these for free.

If you're already using Google Analytics, we recommend putting a new property next to your existing property. By doing this you can compare your current results with the new way of measuring, just like I did above.

Once you have created an account you can send us an email at with your Tracking ID for Google Analytics (UA code). For Facebook tracking we need a Pixel ID and access token from your Facebook Business account.

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