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Why Google Tag Manager Server Tagging is not suited for reliable conversion tracking

Apr 25

3 min read

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In the rapidly evolving digital marketing landscape, the tools and technologies we choose are critical for the success of our online campaigns. Among these, conversion tracking plays a crucial role in understanding the effectiveness of our efforts. While Google Tag Manager (GTM) offers a range of functionalities that simplify the management of digital marketing services, it falls short in providing a robust solution for conversion tracking, especially when it comes to the Server Tagging feature (S2S).



This blog post delves into the critical limitations of using Google Tag Manager for reliable conversion tracking, emphasizing that regular GTM setups struggle with the same issues highlighted below. GTM’s Server-side Tagging attempts to address the limitations of client-side tracking through S2S tracking, but it does not mitigate the challenges faced by marketers today. The core issues stem from two significant dependencies.


· GTM (including Server Side Tagging feature) is dependent on cookies which are becoming increasing vulnerable to browser tracking prevention.


· The reliance on JavaScript to execute in a user’s browser means GTM falls short of being robust solution.

Dependency on Browser-Based Cookies

One of the fundamental limitations of GTM, even with its S2S feature, is its reliance on cookies stored in the user's browser. While cookies are a traditional method for tracking user behaviour across sessions and websites, their effectiveness has been significantly compromised in recent years. Modern web browsers, led by Safari and Firefox, have introduced stringent tracking prevention measures that severely limit the lifespan and accessibility of cookies. This has a direct impact on the reliability of conversion tracking, as the mechanisms GTM relies on to attribute conversions can be easily disrupted or blocked outright.

The Necessity of Google's JavaScript to Run in the Browser

The operation of GTM is heavily dependent on its JavaScript code being executed within the user's browser. This creates a vulnerability, as all it takes to disrupt this process is the user running a browser that has tracking prevention measures or the user installing an ad blocker. These tools are designed to detect and block scripts from Google services, including GTM, as part of their functionality to protect user privacy. The result is a significant portion of your audience that becomes invisible to your tracking efforts, leading to underreported or inaccurate conversion data.

The False Promise of Increased Tracking Resilience

Given the aforementioned challenges, GTM's server-to-server tracking does not effectively address the core issue of resilience against tracking prevention mechanisms and ad blockers. Despite the potential for S2S tracking to bypass some limitations of client-side tracking, its underlying dependency on cookies and Google's JavaScript running in the browser means it falls short of being a robust solution.

With major browsers and a significant number of users employing various forms of tracking prevention, relying on GTM for your conversion tracking needs can result in a substantial underestimation of your marketing campaigns' performance. This gap in tracking can lead to misguided decisions, misallocated budgets, and ultimately, an inaccurate assessment of your marketing ROI.

Moving Forward

In light of these challenges, it's essential to carefully consider the tracking solutions you use and choose those that can offer more reliability and resilience. Tradedoubler offers robust, data-driven tracking solutions mitigating the risks of ad blocking and cookie blocking technologies. With 25 years of experience, Tradedoubler has developed advanced techniques to accurately attribute transactions across different browsers and devices of the same user.

Tradedoubler's approach to combating tracking prevention and ad blocking has shown an uplift of 10-30% correctly attributed conversions. By leveraging Tradedoubler's innovative tracking technologies, marketers can ensure more accurate conversion attribution, ultimately leading to better-informed decisions and optimized marketing strategies.

If you're looking to enhance your conversion tracking setup and mitigate the impacts of ad blockers and tracking prevention, now is the time to act. Contact us to learn more about how our tracking solutions can improve your marketing efforts, providing a clear edge in accurately measuring and attributing conversions in an increasingly challenging digital landscape >>

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