As privacy becomes a dominant concern across the internet, a growing number of users are using ad blockers like uBlock Origin, Pi-hole, and browser-level privacy tools to avoid being tracked. While this protects the user, it introduces significant gaps for businesses trying to understand their customer journey. In this post, we’re diving deep into how Google Tag Manager (GTM) Server-Side helps solve this problem and why it’s becoming essential for every modern business and SaaS app.
The Problem with Traditional Client-Side Tracking
Many businesses rely on tools like Google Ads and Google Analytics to optimize their marketing strategies. These tools depend on client-side scripts—the tags and pixels that are triggered when someone visits a website. These scripts collect critical data points like user location, session activity, conversions, and more. However, if a user is running an ad blocker, many of these scripts—including those from GTM—are never even loaded. As a result, businesses lose visibility into who is visiting their site and what actions they are taking.
For example, using Pi-hole as a network-level blocker completely shuts down the execution of GTM scripts. If Google Tag Manager doesn’t load, then neither do the analytics scripts within it. This means platforms like Google Ads are unable to learn from user behavior, leading to wasted ad spend and missed optimization opportunities.
Why First-Party and Server-Side Tracking Matters
To combat these visibility issues, companies are now turning toward first-party, server-side tracking. This strategy allows event data to be sent from your own server instead of directly from the user’s browser. Since server-side tracking operates from your backend, it's not as easily blocked by ad blockers.
In a typical SaaS setup, you might have a marketing site (e.g., www.example.com) and an app hosted on a subdomain (e.g., app.example.com). Traditional tracking often fails to follow users between these two domains—especially when cookies are blocked or scripts don’t fire. With server-side GTM, you can centralize your tracking infrastructure and monitor cross-domain behavior more reliably.
Real-Time Impact of Ad Blockers on GTM
A real-world test using a local environment revealed exactly how much ad blockers disrupt tracking. When GTM was blocked, all scripts tied to it—including analytics, advertising, and funnel events—failed to execute. Upon whitelisting GTM and refreshing the site, Google Analytics immediately began reporting live user activity again. This experiment illustrates a critical truth: if GTM is blocked, your marketing stack is flying blind.
How Server-Side GTM Solves This
By shifting to Google Tag Manager Server-Side, you regain control over your data. Events are sent from your own backend or cloud server, rather than relying entirely on user-side JavaScript execution. This not only helps bypass ad blockers but also:
- Improves data accuracy and load speed
- Reduces third-party script bloat
- Enhances compliance with privacy regulations like GDPR and CCPA
- Provides flexibility to send data to multiple platforms (Google Ads, Facebook Conversion API, Mixpanel, etc.)
In the upcoming videos and tutorials, we'll explore how to configure GTM server-side using Google Cloud, how to pass user events securely, and how to centralize your marketing and product analytics even when users have advanced privacy tools in place.
Why This Series Matters
This series is created to demystify the behind-the-scenes processes of tracking infrastructure and empower you to build a resilient data flow from your marketing site to your app. Whether you’re running a SaaS business, managing a high-traffic landing page, or tracking mobile apps alongside your web presence, server-side GTM offers a future-proof solution.
If you’re tired of missing key conversion data due to ad blockers, or if you’re preparing your tracking stack for a cookieless future, this guide is for you.
Modern web tracking is evolving quickly. Ad blockers, privacy regulations, and fragmented user journeys make client-side tracking less reliable by the day. Shifting to server-side GTM is not just a technical upgrade—it’s a strategic one. In the next posts, we’ll set up a full server-side GTM environment, configure custom domains, and ensure that your analytics setup works regardless of how many blockers are in play.
Stay tuned, and if you're looking for help setting this up for your own business, reach out via Guru Labs at gurulabs.dev. We specialize in Google Tag Manager, Facebook Pixel, server-side setup, and more.
