London, UK · Serving UK/EU · GBP pricing

Google Tag Manager consultant. Expert implementation & debugging.

Q: Can you fix GTM without breaking existing tracking?

Yes. Existing setups are carefully audited before making changes, everything is tested in Preview mode, and updates are deployed incrementally to minimize disruption. The goal is improving tracking while maintaining data continuity.

Turn your Google Tag Manager from a mess into a marketing advantage.

Google Tag Manager should make tracking simpler. But for most businesses, it becomes a dumping ground for tags, a mystery box no one wants to touch, or worse—a source of broken data that undermines every decision made.

Marc Alexander is an independent Google Tag Manager consultant with nine years of experience building tracking systems that marketing teams can actually trust. He specialises in GTM implementations that are clean, documented, and built to last—whether starting from scratch, inheriting a chaotic setup, or preparing for server-side tracking.

Based in London and working across the UK and EU, Marc helps businesses implement GTM properly the first time, debug broken configurations, and create tracking architectures that support serious growth without becoming technical debt.

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What Marc does as a Google Tag Manager consultant

GTM implementation and setup

Marc builds Google Tag Manager configurations from the ground up, designed around specific business models, conversion events, and measurement needs. This includes container structure, naming conventions, trigger logic, data layer architecture, and documentation so teams know what's happening and why.

GTM audits and debugging

When GTM containers are broken, bloated, or confusing, Marc audits the entire setup, identifies what's firing incorrectly (or not firing at all), cleans up redundant tags, fixes tracking gaps, and documents the state of containers so businesses can move forward with confidence.

Server-side Google Tag Manager

Marc implements server-side GTM to improve data accuracy, reduce client-side script bloat, extend cookie lifespans, and give businesses more control over what data is sent where. This includes setting up Google Cloud infrastructure, migrating tags server-side, and ensuring measurement stays compliant with privacy regulations.

GTM to GA4 integration

Google Tag Manager and GA4 should work together seamlessly. Marc configures GTM to send clean, structured event data to GA4 using best-practice data layer patterns, custom dimensions, and event parameters that make reporting actually useful.

E-commerce tracking setup

For e-commerce businesses, Marc implements complete purchase funnels in GTM—product views, add to cart, checkout steps, transactions, and revenue tracking—integrated with GA4 and any other platforms used (Facebook, Google Ads, TikTok, etc.).

Consent management and privacy compliance

Marc configures GTM to respect user consent properly, implementing Consent Mode v2 for GA4 and Google Ads, ensuring tags fire only when legally allowed, and building privacy-first tracking architectures that comply with GDPR and UK data protection laws.

Custom event tracking

Beyond pageviews and clicks, Marc builds custom event tracking for the actions that matter to businesses—form submissions, video plays, scroll depth, file downloads, button clicks, interactive elements, and any user behaviour that needs measuring.

Data layer strategy and implementation

The data layer is the foundation of reliable GTM tracking. Marc designs and implements data layers that capture the right information at the right time, making it easy to pass contextual data to GA4, advertising platforms, and third-party tools without brittle code dependencies.

Why businesses hire Marc as their Google Tag Manager consultant

Inheriting broken GTM setups that no one understands

Previous agencies or developers leave behind GTM containers that are impossible to debug. Tags fire randomly, nothing is documented, and teams are afraid to touch anything. Marc untangles these messes, documents what's actually happening, and rebuilds containers into systems that make sense.

GTM has become a bloated, unmaintainable mess

Over time, GTM containers accumulate duplicate tags, deprecated triggers, and unused variables that slow down sites and create data quality issues. Marc audits and streamlines containers, removing technical debt and creating clean architectures that teams can actually work with.

Tracking breaks whenever the website changes

When GTM relies on brittle CSS selectors or fragile page structures, every website update breaks tracking. Marc builds resilient GTM setups using proper data layers and stable identifiers that survive redesigns and platform migrations.

Data doesn't match between platforms

GA4 shows one revenue number, the CRM shows another, and advertising platforms report something completely different. Marc implements consistent tracking across all platforms, ensuring data integrity and building trust in analytics.

Need to implement server-side tracking

With third-party cookies dying and ad blockers becoming ubiquitous, businesses need server-side GTM to maintain data accuracy. Marc handles the full implementation—from Google Cloud setup to migrating tags server-side while maintaining measurement continuity.

Marketing team can't make changes without developer help

GTM should empower marketing teams to iterate quickly, but many setups are so complex that every change requires developer intervention. Marc builds documented, user-friendly GTM configurations that marketing teams can safely modify themselves.

Preparing for privacy regulations and consent requirements

GDPR, ePrivacy, and UK data protection laws require careful consent management. Marc implements GTM architectures that respect user privacy, integrate with consent management platforms, and ensure compliance without sacrificing measurement quality.

Need custom tracking for complex user journeys

Standard pageview and click tracking isn't enough for businesses with complex products, multi-step funnels, or unique user interactions. Marc designs custom event taxonomies and implements tracking for the specific behaviours that drive business outcomes.

How Marc approaches Google Tag Manager consulting

Marc's approach to Google Tag Manager consulting combines deep technical expertise with business strategy. Rather than just implementing what's requested, he asks what decisions the data needs to support and builds tracking systems that deliver those insights reliably.

Every GTM implementation starts with understanding the business model, customer journey, and key conversion events. Marc then designs a measurement strategy that captures the right data at the right time, structures it consistently, and makes it accessible across all analytics and marketing platforms.

Technical implementations are always documented. Container structures follow clear naming conventions, triggers are built to be resilient, and data layers are designed to be developer-friendly. The goal is creating GTM setups that teams can understand, maintain, and build upon.

Marc works closely with marketing, product, and development teams to ensure tracking aligns with business needs, integrates cleanly with existing systems, and doesn't create technical debt or performance issues.

Marc's Google Tag Manager expertise includes

Client-side Google Tag Manager configuration and optimization

Server-side GTM implementation using Google Cloud Platform

Data layer design and implementation for single-page applications

GTM to GA4 integration with custom event tracking

E-commerce tracking (enhanced e-commerce, GA4 e-commerce events)

Cross-domain tracking and subdomain configuration

Consent management implementation (Consent Mode v2, CMP integration)

Custom JavaScript variables and advanced trigger logic

Tag sequencing and firing priorities for complex dependencies

GTM debugging using Preview mode, browser developer tools, and Tag Assistant

Integration with advertising platforms (Google Ads, Facebook, LinkedIn, TikTok)

Performance optimization to minimize page load impact

GTM workspace management and version control

Team training and documentation for ongoing maintenance

Google Tag Manager implementation process

Discovery and audit (Week 1)

Marc reviews existing GTM setup (if one exists), audits current tracking, identifies gaps, and documents what's working and what isn't. For new implementations, this phase focuses on understanding business requirements, conversion events, and measurement priorities.

Measurement planning (Week 1-2)

Working with stakeholders, Marc defines what needs to be tracked, how it should be structured, and where data needs to flow. This includes event taxonomy, data layer specifications, and integration requirements with GA4 and other platforms.

GTM configuration (Week 2-4)

Marc builds or rebuilds the GTM container with proper structure, naming conventions, and documentation. This includes tags, triggers, variables, data layer implementation, and integration with GA4, advertising platforms, and any third-party tools.

Testing and quality assurance (Week 3-4)

Every tag is tested in Preview mode and on staging environments. Marc validates that events fire correctly, data is structured properly, consent is respected, and tracking works across devices and browsers.

Deployment and monitoring (Week 4-5)

GTM changes are deployed to production with careful monitoring. Marc tracks data quality, validates accuracy against expected patterns, and makes adjustments as needed during the initial rollout period.

Documentation and handover (Week 5)

Marc provides complete documentation covering container structure, event taxonomy, data layer specifications, how to make common changes, and troubleshooting guidance. Teams receive training on managing the GTM setup going forward.

Google Tag Manager consultant pricing

Marc offers flexible GTM consulting based on project scope and complexity:

GTM Audit: £350 - £800

A comprehensive review of existing GTM setup, identifying issues, data quality problems, and optimization opportunities. Includes written report with prioritized recommendations.

GTM Implementation (New Setup): £800 - £2,500

Clean GTM configuration built from scratch, including container structure, basic event tracking, GA4 integration, and documentation. Pricing depends on site complexity and tracking requirements.

GTM Rebuild (Fixing Broken Setup): £1,200 - £3,500

Complete overhaul of problematic GTM container, cleaning up technical debt, fixing broken tracking, and implementing proper structure with documentation.

Server-Side GTM Implementation: £2,000 - £5,000

Full server-side GTM setup including Google Cloud infrastructure, tag migration, and ongoing monitoring. Pricing varies based on traffic volume and number of tags.

E-commerce GTM Setup: £1,500 - £4,000

Complete purchase funnel tracking for e-commerce sites, including product views, cart interactions, checkout steps, and transaction tracking integrated with GA4 and advertising platforms.

Ongoing GTM Support: £500 - £1,500/month

Monthly retainer for ongoing GTM maintenance, updates, new event implementation, and technical support.

All pricing is in GBP. Projects are scoped individually based on specific requirements.

Common Google Tag Manager questions

How long does a GTM implementation take?

Basic GTM setups typically take 2-3 weeks. More complex implementations with server-side tracking, extensive e-commerce functionality, or significant debugging work can take 4-8 weeks. Marc provides realistic timelines during the discovery phase.

Can you fix GTM without breaking existing tracking?

Yes. Marc carefully audits existing setups before making changes, tests everything in Preview mode, and deploys updates incrementally to minimize disruption. The goal is improving tracking while maintaining data continuity.

Do you provide GTM training for our team?

Absolutely. Marc includes training and documentation with every project so teams can manage ongoing maintenance, make common updates, and understand how their GTM setup works.

What's the difference between client-side and server-side GTM?

Client-side GTM runs in users' browsers and is affected by ad blockers and browser restrictions. Server-side GTM runs on your own infrastructure, giving you more control, better data accuracy, and improved privacy compliance. Marc can explain which approach makes sense for your situation.

Can you integrate GTM with our existing tech stack?

Yes. Marc regularly integrates GTM with e-commerce platforms (Shopify, Magento, WooCommerce), CMS systems (WordPress, Webflow), marketing automation tools, CRMs, and advertising platforms. Integration requirements are discussed during planning.

How do you handle GTM for single-page applications?

Single-page applications require special GTM configuration because traditional pageview triggers don't work. Marc implements history change listeners, custom events, and data layer patterns designed specifically for SPAs.

What happens if tracking breaks after you've finished?

Marc provides post-launch support and can be retained on an ongoing basis for maintenance and updates. All implementations include documentation so teams can troubleshoot common issues independently.

Do you work with agencies or in-house teams?

Both. Marc collaborates with marketing agencies who need GTM expertise for client projects, and works directly with in-house marketing and analytics teams who want independent consultant support.

Ready to make your analytics decision-grade?

Book a free 30-minute consultation to discuss your Google Analytics challenges and explore how Marc can help.

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He's surprisingly friendly, even when telling you your GTM tracking's a disaster.

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