What is server-side tracking?

With the expiration of third-party cookies, shorter lifespan of Safari’s first-party cookies and increased privacy requirements, decision-makers are more concerned about accuracy of their advertising data. Many marketers have been intrigued by the release of Facebook Conversion API and Google Tag Manager Server Side as server-side alternatives to client-side tracking.

In this article, we’ll answer some questions in plain English.

1. What is server-side tracking?
2. What are the advantages of server-side tracking?
3. What is the difference between server-side tracking and cookies managed on the server?
4. Does server-side tracking mitigate ITP 2?
5. Is it worth migrating to server side tracking?

Before we start, here are some definitions of the terms that we’re going to use. You can skip this part, if you are already familiar with web technology.

1. Web browser: tool/software that allows you to navigate the web (Chrome Safari Firefox, Firefox)
2. Web/browser Cookie: is a web browser feature that allows websites to store data for a specified period of time such as anonymous user IDs, preferences, and so on.
3. Web server: infrastructure hosting a website (ex. It then serves web pages to a browser.
4. Marketing/analytics Pixel: A piece of code that is installed on a website to allow marketers to track conversion events, build audiences, and monitor sales funnels
5. Analytics and Ad Servers:a set infrastructure that allows vendors (Google and Facebook) to receive and store data from their users (marketers).
6. ITP2: Intelligent Tracking Prevention (ITP) is a technology by Apple that prevents cross-site tracking by limiting 3rd party cookies and other website data on Safari browsers.

This is a simplified illustration of website architecture

1. What is the difference between server-side and client-side tracking?

Client-side Tracking

A pixel is a small piece of code that allows for analytics and tracking marketing efforts. The pixel is placed on the website and is loaded into the browser of the user when he or she visits the website for the first time. The pixel will create a web cookie, which will be placed in the browser of the user. This cookie will contain an anonymous ID that will allow the user to be identified during interactions with the website (browsing pages, clicking links). The pixel will transmit an event to the analytics/ad server every time the user interacts on the website. It will also attach the anonymous ID stored in the web cookie. This anonymous ID will enable the vendor (Google or Facebook, etc.) to link these events to a user using an anonymous ID. Since this happens in the browser of the user, this process is be called client-side tracking. Note that there are still servers involved: the data is collected in the browser and sent to the analytics servers.

Server-side Tracking

When vendors (Google, Adobe, Facebook, etc.) refer to server-side tracking they usually mean the process of sending data server-to-server. This means from your website server to their server. This is usually invisible to web browsers since it happens on the server of the website. Some kind of user identification (anonymous ID, or any other identifier) is still required; this it can be generated on-the-server side or passed from the web browser to the server.
The use of server-side tracking is not new: it has been around for many years. Many vendors offer server-side functionality (tracking APIs) that can be implemented on a server side. The data is sent directly from the web server to the vendor’s servers (from the vendor’s website to its analytics server).

2. What are the advantages of server-side tracking?

These are the main benefits of migrating client-side tracking implementations to the server side.

1. Improved accuracy because there are fewer user events/conversions lost due to page load time and ad blocking
2. Increased security because the data is hidden from web browsers
3. Performance of your web pages will be improved by having fewer tags or pixels loaded.

Server-side tracking has one drawback: it is more difficult to implement. Some of the client-side data (browser information, IP address, etc.) needs to be collected by you.

3. What is the difference between server-side tracking and web cookies managed on server side?

This is the most complicated question, because the actual difference is subtle for non technical people. Generally speaking, you can also manage your web cookies on the server side. Let’s start by defining some facts about cookies.

You can create web cookies from:

1. Client side (web browser) – For example, an analytics or marketing plugin loaded into your browser creates the cookie.
2. The server side (webserver)- For instance, when a page is requested, the server creates a cookies and sends it back to the browser. These cookies can be used to store sensitive information such as login status and website preferences. Analytics or marketing pixels can’t access the contents of these web cookies most of the time (i.e. JavaScript for technical readers). These cookies are therefore considered safer. These cookies are encouraged by the Safari team at Apple.

Server-side tracking, as explained at the start of this article is the sending of data server-to server, rather than browser-to server. However, to make things a bit complicated: Do not assume that server-side tracking automatically includes web cookies stored on the server side. We’ll elaborate this in the next section.

4. Does server-side tracking mitigate ITP 2?

ITP 2 is specifically designed to target web cookies. ITP 2 has no impact on the lifespan of first party cookies when you manage cookies on the server (at the time of writing). If you want to improve web page performance and accuracy, server-side tracking is the means to achieve just that.

5. Is it worth migrating to server side tracking?

It is important to carefully consider whether server-side tracking would be a good fit for your business. You should ask yourself the following questions:

1. Are you looking to increase the performance of your web pages?
2. Are you looking to conceal sensitive data?
3. Are you looking to increase data accuracy?
4. Are you able to easily access web developers?
5. How do you manage user consent on the server (preventing tracking before user consent)?

Server-side tracking is more complex than traditional tracking and requires some expertise. A little engineering is required (web developers are needed). Google Tag Manager, Adobe Launch, Facebook Conversion API and Segement all offer different versions of server-side tracking. Each of these companies has their own ways to implement server-side tracking.

Feel free to contact us with any questions about website tracking.

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Foto von Matt Hardy von Pexels
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