Complete GTM Audit Guide: How to Audit Google Tag Manager Containers [2025]

Why Every GTM Container Needs Regular Audits

Whether you're taking over a new client's tracking strategy or performing cleanup for your legal team, auditing GTM containers is a critical step for any analytics professional. Yet most audits I've seen follow an ad-hoc approach that misses critical issues.

This guide shares the systematic 10-step framework I've developed through hundreds of client audits. The order follows a logical progression: validating the foundation first, then moving to strategic and architectural questions.

You can't build a house without a plan, and the same goes for any tracking project. Whether you need to identify relevant events with the marketing team or work from an existing tagging plan, having this documentation is mandatory.

You may want to challenge the plan from the start—ensure event naming follows a clear taxonomy (same with page names) and that obvious events (like purchases for an e-commerce store) aren't missing. Building a tagging plan isn't a one-time task but rather a continuous process where you'll leverage insights from your analysis to enrich or remove events.

A common behavior is trying to track everything under the sun. It's your job to ensure only relevant, actionable events get tracked. There's a cost to tracking—mainly in site performance and potential data leaks—so stay lean. An easy compass for deciding what's worth tracking: establish a list of KPIs with business and marketing teams, then ensure all KPIs are materialized in your tagging plan. If not, remvove. If in doubt, remember the saying: when in doubts, there's no doubts. Simply ditch it and move forward.

When performing audits, validate the simplest assumptions first. While it should be obvious that the container is present (developers usually implement it in a component injected on every page), I've experienced this issue numerous times in my career.

If you find missing pages, reach out to your development team with the specific faulty pages so they can fix them quickly.

Any tracking project should have a tagging plan that lists all tracked interactions, conversions, and dataLayer values. Ideally, it should give you hints about where those events occur, with associated expected dataLayer variables and their possible values.

A simple way to check this: build custom reports in your analytics tool to list received values for each dataLayer variable. By comparing received variables with your tagging plan guidelines, you can spot inconsistencies and filter by interaction or page to identify where fixes are needed.

Similarly, dataLayer variables can be implemented on the site but not in Google Tag Manager. Cross-check that every expected variable is correctly mapped to the appropriate events in your container setup.

Now that you've verified GTM is present everywhere and the expected context is ready to be sent alongside your defined events, ensure your triggers are correctly configured. The tagging plan is your friend here—make sure your triggers reflect what's documented.

We've discussed the performance impact of heavy containers. It's a real threat to your performance, affecting not just PageSpeed Insights scores—page performance positively correlates with SEO ranking and conversion rate. You don't want to undermine your SEO team's efforts because of useless tags.

Vendors present in your GTM containers should serve a business objective. I've seen containers with outdated vendors still present even though the company was no longer working with that vendor. Besides, sending user data to vendors you don't have formal agreements with poses high privacy risks. You wouldn't want to get fined for a data breach that could have been avoided by removing tags with two clicks.

For some companies, privacy is an afterthought. They think they'll never get fined because they're too small. The reality is that it's a gamble—huge companies like Meta and American Airlines have been fined for data leaks, but smaller ones too.

Privacy Audit Steps

Now that the foundation is in place, test that your setup works properly. The best approach: open your browser's network tab and go through each implemented event (potentially every page) to check that tags fire correctly, with the right data attached and to the appropriate destination.

Remember: you defined tracking based on KPIs you aim to measure. If you're also the analyst, now's a good time to start building reports and ensure they answer your questions.

Now that you're confident your tracking works correctly, return to the drawing board. Ensure your initial assumptions were correct—that your KPIs and their translation into tracking specifications are actionable and the best way to draw insights on user behavior and marketing performance.

You might find you're missing data to unlock specific insights or, conversely, collecting data that doesn't participate meaningfully in your analysis. Don't hesitate to remove unnecessary tracking—more data is rarely better. Better data is what you should aim for.

Audits are tedious, time-consuming, and sometimes offer little immediate reward. Instead of doing everything again in one shot and losing your sanity, perform targeted audits regularly. This could be validating privacy compliance, refreshing tag lists, reviewing cookies...

Another great solution: team up with your development team to implement basic unit testing and checks. This might not always be feasible, but when possible, it prevents the stress of discovering you've been missing a key variable for two weeks because a site change broke your tracking.

There's nothing more frustrating than spending days or weeks building a detailed audit only to realize nobody's reading it or taking action. It's tempting to stuff everything you can into those reports to showcase your hard work.

Showing fifty pages of audits might feel like a good way to prove your value to immature customers who haven't developed data-driven strategies. They'll like that an audit was performed, even though they won't go through the results.

For mature customers, make audits actionable. Highlight issues and corresponding solutions in plain English, without jargon. Your audience should have a clear picture of risks and a roadmap to address them. Cut through the noise to keep only the signal.

Conclusion: Your GTM Audit Toolkit

This 10-step framework will help you approach audits with more confidence and thoroughness. Audits can be scary, but like you would not want to ride your car without revising the enigne regularly, your data vehicle also needs care and checks from times to times to help you and your company take action on the best data possible, safely.

Remember: regular maintenance is easier than comprehensive overhauls. Schedule ongoing audits, collaborate with your development team, and always keep your users' privacy at the forefront of your tracking strategy.