Server-Side Tracking: Why It's Time to Make the Switch

Insights / 05.26.2021

1/30/2024 6:51:36 PM Red Door Interactive http://www.reddoor.biz Red Door Interactive

In the past, when marketers wanted to analyze how consumers interacted with their product online, they had to rely on tracking code snippets that send data from the web browser to tools such as Google Analytics.

However, with the continued rise of data privacy restrictions, ad-blockers, and privacy-aware web browsers, this approach is becoming less of an option. In short, marketers are going to have a tougher time understanding how their product is used and where their visitors are coming from. But don’t panic, there’s a solution: server-side tracking.


The most common approach to website tracking involves a small snippet of code (i.e. a tracking tag) hard-coded into the front-end of a web page, or placed within a tag management platform. These tags may request scripting from a 3rd party to gather all required information and then make a request for a small image (i.e. tracking pixel) from the platform. This process allows the platform to capture details about the user by sorting through more information included within the image request. Server-side tracking seeks to limit the amount of code running in the browser. It offloads many of the steps above onto a server, where brands have more control. This can also accelerate page performance by eliminating the amount of work required in the browser.


Server-side tagging has long been available as a way to implement web tracking, but the expansion in the number of web tags — and limited visibility by marketers — created challenges. But thankfully, newer capabilities from the most popular tag management and marketing platforms have lowered those barriers.


In 2020, Google announced the deployment of server-side GTM to public beta, providing an accessible, free option to introduce server-side tagging within their widely-used tag management platform. While still in public beta (at the time of this post), Google continues to add critical new capabilities to increase adoption, and vendors are beginning to support their templates for use within server-side GTM.


Web Vitals are a group of metrics created by Google to help site owners understand the performance-impacting factors that support the best website experience. Core Web Vitals are a subset of these metrics deemed most critical for site owners to monitor and optimize, and Google has gradually been surfacing Core Web Vitals across several tools. Here is a summary of the Core Web Vitals for 2021, which may evolve (as defined on the dedicated web.dev/vitals site):

  • Largest Contentful Paint (LCP): Measures loading performance. LCP should occur within 2.5 seconds of when the page first starts loading to provide a good user experience.

  • First Input Delay (FID): Measures interactivity. To provide a good user experience, pages should have an FID of 100 milliseconds or less.

  • Cumulative Layout Shift (CLS): Measures visual stability. To provide a good user experience, pages should maintain a CLS of 0.1 or less.

Critically, Google has announced that beginning in June 2021, Core Web Vitals will be included as a ranking factor in organic search. Naturally, anything that improves Core Web Vital scores and page performance requires more urgency, and server-side tagging provides immediate ROI in the way of faster load times to support search rankings.


The current version of Safari's Intelligent Tracking Prevention (ITP 2.3) — introduced in the much-discussed iOS 14 updates — restricts the lifetime of first-party JavaScript cookies to 1 or 7 days (24 hours for known trackers). For marketers, the reduction in cookie lifetime means that all Facebook, Google Analytics, and other cookies set by analytics and media platforms will be deleted after just 24 hours, severely undermining the accuracy of remarketing audiences and comprehensive tracking data for Safari users. However, with server-side tagging, we can build more resilient cookies not subject to ITP limit and restore the full lifetime of those cookies.

Aside from Safari browser implications, certain ad blockers can prevent tracking from occurring by blocking requests to known tracking domains, such as google-analytics.com. With fully deployed server-side tagging, these requests are directed to a subdomain of your brand (ex: metrics.yourdomain.com), allowing tracking to continue where appropriate.

Note: Care should be taken to respect user consent via a consent management platform or other solution as part of your brand's privacy protection measures. Preventing ad blockers from also blocking marketing pixels may or may not be part of these considerations.


When viewed through the lens of a marketer, the benefits of server-side tagging extend into several areas of digital marketing and operations, including:


Moving to server-side tracking enables use of the Facebook Conversions API with advanced matching for attributing conversions. This lowers the cost-per-acquisition via higher conversion volume captured and better data for optimization — even without making campaign adjustments — because better data can be fed into media algorithms for automatic optimization.

Furthermore, where cookies are still necessary, these can now be set more persistently and not automatically expired by Safari, restoring the ability to build effective retargeting audiences that include Safari users.

Finally, the performance of landing pages is a critical factor in the performance of media campaigns, with Google introducing Mobile Speed Score to understand landing page performance, back in 2018. Improving load time via server-side tagging should provide an immediate benefit to your media performance.


In line with Core Web Vitals, moving additional scripting and server calls out of the browser and onto a server allows pages to load faster and tracking scripts to load from your first-party domain versus a 3rd party domain.


With your own brand's first-party domain responding to requests for trackers (for example, GA /collect) and tracking scripts such as analytics.js and gtag.js, you now have a way to set tracking cookies in a more trusted manner - HTTP cookies - for Safari ITP. This restores full cookie lifetimes instead of 1- or 7-day expiration, and ensures better decisions based on unique users.


It is well-documented that faster load times increase the likelihood of conversions. Now that I've stated the obvious, it's also important to mention the effect of more resilient cookies — as a by-product of server-side tagging — in running an effective testing program.

For example, let's say a Safari user visits your site and is assigned into a test group or experience, then the cookie expires after 24 hours. When that user arrives back without a cookie, they are no longer segmented into a group and may get assigned to a new experience. This scenario hurts both the likelihood of conversion and the integrity of your testing data. Server-side tagging can help prevent this occurrence, and many CRO tools — including Google Optimize and Optimizely — fully support server-side experiments as well.


The topic of website security and Content Security Policies is too big for this post – but it's essential to recognize that by moving trusted scripts server-side and making requests through your domain, you can now institute more strict Content Security Policies.

These more stringent Content Security Policies prevent rogue scripts and 3rd party requests from occurring without you knowing about it. Server-side tracking allows marketers to preserve necessary tracking, while also satisfying the needs of your brand's Information Security teams.


Migrating to server-side tracking is an obvious step in the evolution of web tracking, given the current privacy landscape and advanced capabilities provided by such a setup. With the newer capabilities in server-side tag management, growing support by analytics and media platforms to lower the barriers, ability to get better data, and the option to iteratively move more tagging server-side without disrupting current tracking, there's little reason not to explore the server-side approach.

Considering growing iOS and other privacy restrictions, as well as Google's Core Web Vitals ranking update, we highly recommend making the switch to server-side tagging. Red Door’s Analytics team has experience in deploying server-side tracking in a way that preserves and extends existing tracking, while also providing dramatic improvements to site speed. Interested in learning more about this approach? Reach out – we’re here to help.

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