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Server-side tracking vs client-side tracking: What are the trade-offs when collecting data?
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Server-side tracking vs client-side tracking: What are the trade-offs when collecting data?

Published  

7/22/2021

by 

Stefan Santer

7
min read

Published  

July 22, 2021

by 

Stefan Santer

10 min read
Summary

Tracking blockers, vendors who do not respect regulations (learn more about the IAB TCF), and browser restrictions like Safari's intelligent tracking prevention or FireFox's enhanced tracking protection reduce data quality and increase legal risk in digital marketing.

Server-side tracking offers a solution that relies on first-party data, reducing such restrictions and enhancing website performance by eliminating the need for tracking scripts and pixels to load on the client's device.

How do you determine whether to track your users server-side or client-side? Which option is the best choice for you? Continue reading for more information. 

The decline of client-side tracking 

Client-side tracking is the most common form of data collection. This type of tracking involves collecting data from a user’s browser, most likely via tag management, such as Google Tag Manager. 

 

However, the increasing use of adblockers reduces the capacity of client-side tracking, acting as an obstacle in the digital advertising ecosystem. The problem becomes more prominent when we consider the increasing restrictions on third-party cookies, which are on their way out (see Google third-party cookie phase-out for more context).

 

If not enough valid data is available, browser-based tracking goes hand in hand with losing data quality. Marketing activities become more difficult, resulting in reduced customer engagement and ineffectively used budgets.

  

What does it mean to track server-side versus client-side?

It’s clear that with the phase-out of third-party cookies, client-side tracking will become increasingly problematic. The limitations of client-side tracking significantly impact event data accuracy and control.

While client-side tracking is still the most common method of data collection, an alternative is becoming increasingly prominent: server-side tracking

What is server-side tracking? 

On the web, the client is a web browser or mobile device—whatever the user is using to navigate the internet. The server is a computer that returns content to be rendered in the browser or mobile app.

Server-side tracking (cloud delivery) is commonly described as events and data collected on the server from the client. The process follows when the server requests any final configured endpoint. This is commonly known as a tag or a "pixel" request. The difference is that the server sends a request to the final endpoint instead of a direct request from the client.

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What are the main differences between client-side and server-side tracking?

Both server-side and client-side tracking have benefits. And it’s not a question of choosing one over the other—server-side tracking can be used as a supplement to client-side tracking. 

 

But let's look at what  the main differences are, and which type of tracking best suits your needs? 

 

Benefits of client-side tracking

Despite concerns about the phase out of client-side tracking, there are some key benefits to this form of data collection. 

  • Direct access to data: Since the client-side tracking is about the user's device, this form of data collection gives direct access to more concrete user data that could be used for ad targeting.
  • Implementation: Since client-side tracking has been commonly used, it's often seen as the standard option. Therefore, it's usually easy to implement with a pre-prepared code snippet. 
  • Lower cost: client-side tracking is usually considered a lower cost than server-side.

Benefits of server-side tracking

However, server-side tracking can be seen as a more reliable, secure and controllable way to track events, as it does not request directly from a client’s browser. This makes it very useful when dealing with sensitive information. Tracking data on the client-side often faces challenges such as browser restrictions and adblockers, which server-side tracking can also mitigate.

 

Here are some key advantages of server-side tracking: 

  • More control over the data and higher security: Self-collected data remains in the advertiser's control and cannot be viewed or used by third-party providers, which gives the company more security.
  • More independence: Server-side tracking makes companies less dependent on browsers, minimizing problems like browser restrictions or adblockers.
  • Optimized analytics and marketing: The data collected can be used as a base for marketing automation, analytics, and personalization tools.
  • Smoother user experience: Server-side removes some of the limitations associated with the lifetime of cookies. As a consequence, third-party solution that need user interaction (like your CMP) don't require to be resurfaced as often.
  • Increased site speed: Much higher site speed regarding the front-end since no analytics pixels could get in the way. Since server-side can speed up your site's speed, it will improve user experience and SEO. 

 

Nonetheless, it is worth noting that server-side tracking requires the maintenance of an additional tech infrastructure, which can be expensive.

Client-side vs server-side: Comparison table

Compariosn table showing the main differences between client-side and server-side tracking. Client-side: - Direct access to data - Easier implementation - Affordable  Server-side: - More control and increased security - Independence from browsers restrictions - Optimized analytics & marketing - Smoother user experience - Increased website performance

When should you use client-side tracking versus server-side tracking?

Put simply, there are advantages and disadvantages to both client-side and server-side tracking. Therefore, it’s important to consider all the aspects regarding which tracking alternative is the most fitting for your company. We think you should consider several aspects depending on your circumstances, engineering resources, and, of course, how you value privacy. 

Data sovereignty

By not using browser tracking, no client-side data processing is required. Self-collected data remains in control of the advertiser and cannot be viewed or used by third-party providers.

Server-side tracking is an essential component of consistent first-party data management, which is becoming increasingly popular in the industry as an alternative to third-party data.

 

Level of security

Server-side data processing provides more security. Directly implementing data collection on the server is particularly suitable for companies that work with sensitive and business-critical data, such as banks, financial service providers, or online retailers.

However, it is always important to ensure that the collected data is handled as carefully as client-side data and checked for compliance with data protection guidelines. At the same time, it is also necessary to inform the user about the collection and processing of the data.

 

Engineering capabilities

While server-side tracking offers advantages in control, security, and data quality, it’s important to recognize that not all data collection events can or should be moved server-side.

Certain elements, like interactive features or specific types of user data (such as precise geolocation or on-page behavior), rely on real-time data that the user’s browser provides directly. In these cases, client-side tracking is still necessary to capture accurate and immediate data. For most organizations, the ideal approach is a balanced solution that combines server-side and client-side tracking.

Performance

Server-side tracking offers distinct performance benefits by improving data reliability, optimizing website speed, and simplifying maintenance. By collecting data on the server, organizations are bale to bypass ad blockers, ensuring consistent data for ad monetization and personalization. This setup also removes the need for JavaScript tracking scripts on the front end, leading to faster page load times, which benefits SEO and user experience.

On top of that, server-side tracking centralizes data management, reducing reliance on third-party scripts that can be difficult to debug and prone to errors. With direct server communication, you can gain hands-on control over data flow, simplify maintenance, and enhance overall site stability.

User matching

This is the most complex obstacle to server-side targeting. Third-party cookies, used for “user matching” or figuring out the anonymous ID corresponding to a user and matching that up to an advertiser’s anonymous ID for that user, do not exist when server-side targeting. 

 

In summary, third-party cookies can only be read via web browsers, not on servers. However, as the gradual phase-out of third-party cookies is underway, more publishers are testing first-party and ID solutions. 

 

How can Didomi help you to be compliant while using a server-side solution?

It is important to know that user consent is always critical for data collection, even in a server-side solution. We provide different ways to integrate our platform within a server-side solution. In fact, some of our clients are using this already.

 

Didomi provides several ways to use our Consent Management Platform (CMP) server-side, instead of, or in addition to, client-side. To learn more, check out our CMP page and get in touch with our team:

 

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