+3.8 percentage-point increase in returning users tracked in an A/B test: client-side only vs server-side tracking | dofollow

dofollow, a partner of Stape, known for its forward-thinking digital strategies, conducted an A/B testing experiment in collaboration with a Dutch Research Institute to compare the effectiveness of client-side and server-side tracking technologies. This experiment, initiated in October and observed until the end of November 2023, aimed to directly compare the two tracking methodologies by running them concurrently on the institute's website.

The A/B testing approach allowed for simultaneous tracking using both client-side and server-side methods on website traffic to ensure an equitable and comprehensive comparison. Google Analytics 4 was used as data analysis tool.

• Total User Count: The analysis revealed a noteworthy increase in total users recorded via server-side tracking. SST registered 68,904 users compared to the 65,727 users detected through client-side tracking, marking a +5% increase favoring the server-side methodology.
• Recurring Users: A significant disparity was observed in the count of recurring users. Client-side tracking identified 1,216 recurring users, constituting 1.8% of the total user base. Conversely, server-side tracking reported 3,857 recurring users, amounting to 5.6% of the total. This indicates that SST was capable of recognizing over twice the number of recurring users compared to its client-side counterpart.

The pilot study also projected that the gap in recurring user statistics would only widen over time. This projection is underpinned by the durability of cookies with SST, which are retained for 365 days across all browsers, as opposed to the reduced lifespan of cookies in non-Google Chrome browsers under client-side tracking, which ranges from 7 to 31 days.

• Privacy: SST offers enhanced privacy features by allowing control over the data shared with third-party platforms. For instance, it enables the anonymized transmission of statistical data directly to Facebook's Conversion API, circumventing the need for cookie declarations and avoiding breaches of privacy regulations.
• Website Speed: By relocating tracking logic from the web browser to the server, SST significantly improves website speed. It reduces the need for multiple tracking codes to be loaded by the user's browser, thus enhancing the user experience.

The setup conducted by dofollow unequivocally demonstrates the superior capabilities of server-side tracking over traditional client-side tracking methods. Not only does SST offer more accurate and reliable data by capturing a greater number of total and recurring users, but it also brings substantial privacy and website performance benefits. This experiment marks SST as a pivotal investment for the future, ensuring resilience against the increasing browser restrictions on tracking. The success of this pilot paves the way for broader adoption and further exploration of server-side tracking technologies in enhancing online marketing effectiveness. If you want to run your own experiments with cleaner data, our guide to server-side A/B testing walks through how to set it up and what to expect.