What is Server-Side Tagging¶

General introduction to tagging¶

The fundamental goal of any website or application is to deliver valuable content to its users, whether it's an engaging blog post, a seamless shopping experience, or entertaining video content. However, beyond simply providing content, website and app owners are keenly interested in understanding user behavior. They want to identify which content resonates most strongly with their audience and, crucially, how to attract more users who will actively engage with that content.

To achieve this, websites and apps collect data about their use. This data encompasses details about the content being presented to users and, more importantly, how those users interact with that content. This process of attaching secondary information to user interactions is commonly referred to as tagging.

What is tagging¶

At its core, tagging is the practice of associating a user's specific actions on a website or app with the collection of data about that action. For instance, when a user clicks an "add to cart" button, this action isn't just a simple click; it's tagged with additional code. This code transmits valuable information about the activity to specific tools in which it can be used for different purposes.

The multitude of tool vendors and their applications¶

In practice, virtually every website or app will contain multiple tags of a multitude of tool vendors. Each of these vendors offers specialized solutions designed to address specific problems for the website operators. These solutions are incredibly diverse, encompassing:

• Pure statistical analysis: Tools like Google Analytics or Piwik Pro that provide comprehensive insights into website traffic, user demographics, and general engagement patterns.

• A/B testing: Platforms that enable operators to test different versions of web pages or features to determine which performs best in terms of user engagement and conversion rates.

• Evaluation of advertising efforts: Tools that track the effectiveness of marketing campaigns, providing data on ad impressions, clicks, conversions, and return on ad spend.

• Personalization of ads: Sophisticated systems that use collected user data to deliver highly relevant and personalized advertisements, enhancing the likelihood of user interest and conversion.

Client-side vs server-side tagging¶

Historically, websites primarily executed tags client-side, meaning directly on the user's device. This approach was largely due to the high cost and limited availability of servers at the time.

However, this client-side tagging method presents significant privacy challenges. The deployment of tags, as described above, typically necessitates integrating tracking code directly provided by third-party tool suppliers like Google Analytics, Facebook, and other marketing platforms. If the tool suppliers provide the code, the website owners only have limited ability to restrict what data the code will collect and how the tool will store it. Therefore, the core of the privacy dilemma lies in two fundamental principles: transparency and control:

• Problem for user control: If website owners lack control over the data collected by third-party tags, they are unable to offer that same level of control to their users.

• Problem for transparency: Tool providers can sometimes be opaque about the actual data they collect, for instance, through the creation of fingerprints, further eroding trust and user understanding.

Server-side tagging directly addresses both of these privacy concerns. With server-side tagging, a central server, rather than the user's device, executes the tags that share data with third-party tool vendors. This central server empowers website operators with full control over what data they share with specific tool providers and under what circumstances.

Usercentrics Server-Side Tagging¶

The simplest and most efficient method for getting started with server-side tagging is through Usercentrics Server-Side Tagging. This solution offers a fully managed server-side Google Tag Manager (GTM) hosting environment, eliminating the complexities typically associated with self-hosting.

Usercentrics Server-Side Tagging addresses two primary challenges when running a tagging server simultaneously:

• Server management: It completely abstracts away the need for organizations to run and maintain their own servers. This includes concerns about server uptime, performance optimization, security updates, and scalability. By handling these operational burdens, Usercentrics allows businesses to focus on their core activities rather than infrastructure management.

• Leveraging Google Tag Manager: On the other side, the solution harnesses the power of Google Tag Manager, which is the most widely adopted and recognized solution for managing website and app tags. The use of GTM as the operating system for your server-side tagging brings several significant advantages:

• Near-ubiquitous adoption: GTM is extensively used by analysts and marketers globally, ensuring familiarity and ease of collaboration within marketing and analytics teams.

• Consistent principles: It operates on the same foundational principles as other GTM deployment types (e.g., web GTM), making the transition to server-side tagging smoother for those already familiar with the platform.

• Extensive template gallery: GTM boasts a vast and ever-growing gallery of pre-built templates. These templates, contributed by Google and a large community of external developers, cover an immense range of use cases, from basic analytics tracking to advanced conversion measurement and advertising integrations. This rich resource significantly accelerates deployment and reduces the need for custom coding.

How can Usercentrics Server-Side Tagging improve user privacy¶

By the nature of how client-side tagging works, each client side tag will always communicate all HTTP-headers and cookies to the recipient server - even if unintended or unnecessary for the purpose of the tool (Flow 1 below). Server-side tagging instead will allow organizations to share only the essential data with tool vendors, preventing unnecessary oversharing (Flow 2 below). Thus, Usercentrics Server-Side Tagging offers a significant privacy advantage as it enables truly purpose-limited data processing.

In practice, this mainly takes shape in the following two forms:

• Data cleaning for every tool: Before any interaction data is sent to a specific tool (e.g., an analytics platform, an advertising network), server-side processes can be configured to recognize personally identifying information like email-addresses and the payload and protect it from being shared. This ensures that sensitive personal identifiers are removed or anonymized, preventing them from being shared with third parties when not authorized or necessary while still sharing some valuable data with the tool.

• Prevention of unintended fingerprint-ability: Fingerprints often rely on HTTP-headers such as the User-Agent, IP-address, or other traces of the device. Different from a client-side tagging setup, a server-side tagging setup does not share such HTTP-headers with third-parties by default. Thus, organizations can actively prevent the creation of fingerprints that could uniquely identify users without their knowledge.

Benefits for advertisers and analysts of server-side tagging¶

Next to privacy, there are also benefits from a business perspective. For example, it allows for the server-side integration of multiple vendors based on a single request coming from the user’s device. This consolidation leads to a cleaner, more resilient tagging setup, where all integrated tools benefit from a consistent, high-quality data stream. This consistency is crucial for minimizing discrepancies between events reported to different platforms, such as pageview events sent to Facebook versus those sent to Google Analytics, ensuring a unified and accurate understanding of user behavior across all marketing and analytics tools.

Furthermore, server-side tagging provides unique capabilities for data collection and analysis:

• Collection of anonymous data:

  Even when personal data is not available due to user consent choices, server-side tagging enables the collection of valuable anonymous insights into website usage. This capability is vital for understanding aggregated user behavior without compromising privacy. Examples include:

  • Insights into consent banner usage:

    Monitoring how users interact with the consent banner—whether they accept, reject, or ignore it—can provide critical information for optimizing consent management strategies and improving user experience.

  • Evaluation of advertising campaigns with non-consenting users:

    By observing the behavior of users who do not interact with the consent banner at all, businesses can identify potential sources of low-quality traffic from advertising campaigns. This allows for more precise campaign optimization, reducing wasted ad spend on irrelevant or disengaged audiences.

• Integration of sensitive data without user disclosure:

  Server-side tagging facilitates the secure integration of highly sensitive business data without exposing it directly to the user's browser or public-facing systems. This opens up new avenues for advanced analytics and advertising optimization:

  • Optimization with high-value signals:

    Key business metrics such as product margins, customer lifetime value, and conversion probability can be securely attached to events. This allows advertising campaigns to be optimized for these high-value signals, leading to more impactful results compared to relying on noisy or less indicative signals like transaction count or raw revenue. By feeding these richer, more meaningful data points into advertising algorithms, businesses can achieve a deeper understanding of campaign effectiveness and drive more profitable outcomes.