Audit GTM Medium

Google Tag Manager Audit

Well, if you're here, you already have an idea of how important Google Tag Manager can be. After years of quick fixes and tests, that container needs a health check. We'll document every bug, walk you through the findings, and provide solutions to get your GTM back in shape.

6-12 hours

Why Your GTM Container Needs an Audit

Well, if you're here, you already have an idea of how important Google Tag Manager can be for your tracking. If properly used as a single source of truth, it helps orchestrate all the Analytics and Marketing vendors' tagging, making it an easier solution compared to code scattered across your codebase.

But Google Tag Manager is still code in the end. It's a big JSON file, and after years of quick fixes and tests, those heavy-JS HTML tags might not be a good idea anymore.

And yes, Google Tag Manager performance is a thing. Not much about the whole size of this big JSON, but the way the JavaScript code written there interacts with the rest of your site.

Some funny things we've seen during our audits:

Old HTML tags heavy on recursive code to… Just get a parent class.
Loading script of vendors not used anymore on the website… Like, an old Cookie Management Script that automatically blocked all the non-whitelisted cookies
10-20 Google Ads conversions where only a few variables changed. Yes, GTM supports Lookup tables with dynamic variable assignment.
Actually pretty scary: JS artefacts. Obsolete, obscure code that will make you question all the decisions in your life.

You might be surprised by the number of scary, useless things your GTM container has that you can refactor within a week and then be free (until the next shiny tool bought by marketing needs you to refactor the entire GTM to get 0.1% more conversion. Well, if you fell for it, that's on you 🙂)

How We Audit Your Container

We'll not bore you with the details, but as in everything in life, there are good and bad audits.

We don't take your GTM container and put it in the next AI shiny tool and wait for the results. Yes, some "agencies" do that. I'm not criticizing that much, but why should you pay for something you can do with an AI subscription?

I can understand using an LLM trained specifically on tagging, but as of today, the world doesn't yet have an LLM that can work well with the infinite nuances of a Martech stack.

Our approach can be summarised as follows:

Initial Mapping

Initial mapping of all the Tags, triggers, and variables of your GTM container

Redundancy Check

Check for abandoned and redundant elements across the container

Custom Code Review

Custom HTML or JavaScript will be documented and tested against possible edge cases

Performance Audit

Performance Audit of your GTM. Not only about its size, but also about how much it influences the user experience. One thing is performance on pageload measured by tools like webpagetest.org or gtmetrix.com, and another is actually measuring how a heavy GTM container and the code loaded from it affects the interaction with the website.

GDPR Compliance Audit

Not much to say about this one, but you might be surprised by how often marketing vendors say their tool is compliant, even though it's actually tracking your eyeballs on the screen.

What Marketing and Analytics Vendor we test?

We do many other checks based on specific vendors' tags like GA4, Meta, Google Ads, etc.. Each setup has its own hiccups that need to be solved on a case-by-case basis, but overall, they all come down to one important bit:

For each element in the GTM, you must know:

What it is
What it does
And why it was set up that way.

These are the questions we answer for each element in your GTM.

Deliverables

Nice talk, but what about the actual deliverables? Well, here they are:

Document every bug encountered in the tracking stack
Walking through every finding with your team in a call
Container Health Report Full breakdown of every tag, trigger, and variable with detailed explanations for each
Suggestions to reduce the impact on the website performance of your Google Tag Manager
GDPR Consent Compliance report for all GTM elements
Solutions to these problems Or at least the commitment to find one together as soon as possible. After all, fixes don't grow on trees.

Why We're Different

No AI shortcuts. We don't dump your container into an AI tool and call it a day. Each audit is manual, technical, and thorough.

Real-world edge cases. We test your custom HTML and JavaScript against multiple scenarios trying to simulate real-world edge cases that might break in production.

Performance-focused. We don't just check if tags fire we measure how they affect page speed, user interaction, and Core Web Vitals. Heavy GTM containers slow down websites, and we show you exactly how.

GDPR reality check. Marketing vendors love to say 'we're compliant'. We verify it. We flag tags that bypass consent mode and could create legal exposure.

Solutions, not just problems. Every finding comes with a fix. We don't hand you a report and disappear, we commit to solving problems together.

Post-audit monitoring included. After cleanup, you get 1 month free of AssertionHub to automatically monitor your GTM and catch issues before they accumulate again. Read more about AssertionHub.

Frequently Asked Questions

Do you need admin access to our GTM?

Read access is sufficient for the audit. We never publish changes to your container all recommendations are documented for your team to implement (or we implement them as a separate engagement).

How is this different from GTM's built-in diagnostics?

GTM's diagnostics catch basic errors like missing triggers. Our audit goes far deeper we analyze naming conventions, identify duplicate functionality across tags, measure performance impact, check consent compliance, and evaluate the overall architecture.

Can you also implement the fixes?

Yes. The audit and implementation are separate so there's no conflict of interest. But we're happy to implement everything after you've reviewed the report. Many clients prefer this approach.

We use Tealium / Adobe Launch, not GTM. Can you help?

While the timing may be different for Tealium and Adobe, we audit those platforms too

What if we have multiple GTM containers?

The base scope covers one web container. Additional containers (including server-side) are quoted separately. Multi-container setups are common and we often audit them together since cross-container issues are a frequent source of problems.

Prerequisites

• Read access to GTM container
• Access to site (staging or production)

Assumptions (for 6-12 hours)

• Single GTM web container
• Up to 100 tags