In today's digital landscape, data-driven decision-making is paramount for the success of any eCommerce business, especially in the competitive industry like fashion or any other FMCG. Google Analytics 4 (GA4) emerges as a powerful tool, tailored to meet the evolving needs of eCommerce businesses.

GA4 marks a substantial upgrade from Universal Analytics, prioritising event-based tracking for finer data granularity. Its user-centric approach facilitates seamless cross-device tracking, while enhanced machine learning offers predictive insights for personalised marketing strategies accordingly.  

To effectively leverage the capabilities of GA4, it's crucial to have a robust data architecture in place. A well-structured Data Layer serves as the backbone of this architecture, unifying diverse data sources and providing a centralised framework for storage and retrieval. This enables businesses to turn raw information into actionable insights and make data-driven decisions with ease.  

However, these implementations come with challenges that need to be addressed in order for your business to track relevant KPIs and empower data-driven initiatives. 

The aim of this article is to provide a technical implementation guide for seamlessly integrating GA4 into your eCommerce platform, enabling businesses to gain deeper insights into customer behaviour and optimise their online strategies effectively. 

To ensure a successful and comprehensive setup of Google Analytics 4 (GA4), follow these implementation guidelines: 

Prior to delving into the setup process, businesses must first outline their objectives and requirements. This includes determining the deployment scope of GA4, whether it's for a website, an app, or both. Based on this decision, tailor your implementation plan accordingly. 

1. Define objectives and establish the Analytics account setup

This is the most crucial and strategic step for any organisation to define the objective of setting up GA4. It involves decision making for better management and utilising the full potential of GA4, by structuring your Organisational account and set up accounts & properties for multi-brand structure (esp. for larger organisations)

Organisation Account: At the top level, create an organisation account to manage user permissions, billing, and link multiple GA4 properties.

Accounts: Within the organisation account, create one or more accounts. Each account typically represents a distinct business or brand.

Properties: Under each account, create properties. A property can represent a website, a mobile app, or a web+app combination. GA4 properties can be used to track a single domain or multiple domains if they are part of a unified user experience.

2. Set up a GA4 Property

Set up a new GA4 property in your Google Analytics account dedicated to your website or app. This provides a clean slate for configuration and tracking.

3. Configure Data Streams 

Set up data streams within your GA4 property for each platform you want to track, such as web, iOS, or Android. This ensures that data is collected accurately from different sources, as illustrated below.


If your business operates across multiple platforms, such as web and app configurations, simply create multiple DataStreams on GA4 for each platform and follow the outlined setup steps.

Continuing from the previous step, follow the guidance provided by Google to generate a Measurement ID. This unique identifier is essential for seamlessly integrating GA4 into your website or application.


4. Configure and install tracking code

Define your event tracking plan and utilise Google Tag Manager (GTM) to implement the GA4 tags on your website or app.

App implementation

Set up an App SDK for your Firebase [FF1] [AS2] project to smoothly integrate GA4 with your application. Afterwards, download and incorporate the SDK into your app environment. The app development team must configure the SDK in alignment with the predefined tracking specifications.

Web implementation

The process of implementing GA4 on the web follows similar steps to the app implementation, with notable distinctions in the technical setup. Instead of utilizing an App SDK, you have two options for web implementation: Google Tag Manager or the gtag.js method*.

*What are these and how they are different from each other? gtag.js is a JavaScript code library that can be installed directly on your website source code by a developer. By default, the gtag.js already tracks standard events like page views, clicks, video view, etc. For custom events, you need to ask your developer team to set up a gtag.js for each event. Following the Set up Events for gtag.is rules and set the events you want to collect.

The subsequent steps involve defining and setting up tracking events. Events encompass various actions performed within the app, such as clicking a button or viewing a banner. Conversions represent pivotal events for your business, such as completing a purchase or submitting a request form. 

By default, GA4 already captures some fundamental events, including app openings and video views. 

  • Configure GTM to fire the GA4 tags on all relevant pages, ensuring comprehensive data collection. 

  • Custom event tracking to capture specific user interactions such as product views, add to cart actions, purchases, and more.

5. Enable enhanced measurement 

Take advantage of GA4's enhanced measurement features to automatically track common user interactions such as page views, scrolls, outbound clicks, and site searches. Enable relevant options based on your tracking requirements.


6. Implement enhanced eCommerce (EE events) tracking 

If you're running an eCommerce platform, enable enhanced eCommerce tracking to capture detailed data on product views, add to carts, purchases, and other transaction-related metrics. Configure product and promotion parameters to ensure accurate reporting. Harness data layer variables in GTM to dynamically transmit relevant eCommerce data to GA4, ensuring precise tracking of user interactions. 


7. Setup user identity and enable cross-platform tracking 

Implement user identity tracking to associate user interactions across devices and sessions. Utilize user IDs or Google Signals to enable cross-device tracking and gain a comprehensive view of user behaviour 


8. Define and setup custom events & parameters 

Identify and define custom events that align with your business objectives but are not covered by enhanced measurement. These could include actions like form submissions, video views, or interactions with specific elements on your website or app. You have the option to configure these custom events within the GA4 interface.

9. Mark key events as conversion

Determine which events are pivotal for achieving your goals and assign them as conversion events in GA4. These might include purchase or sign-up events. 

Balance between what is been tracked (amount of events, dimensions and metrics tracked) and the cost of having a lot.

10. Integrate with marketing platforms 

You can connect GA4 with other Google products within the suite, including platforms like Google Ads, Google Marketing Platform, and email marketing tools, to harness data-driven insights for tailored campaigns. 

You must set up the right UTM builder to integrate other marketing channels such as Meta, Affiliates etc. using standard tracking parameters. 

Utilise GA4's audience integration features to create remarketing lists based on user behaviour and characteristics. 

11. Configure filters and views 

Apply filters to your GA4 views to exclude internal traffic, spam, or other irrelevant data. Create different views to segment your data based on specific criteria, such as geographic location or user demographics. 

12. Test and debug 

Thoroughly test your GA4 setup to ensure that data is being collected accurately and matches your expectations. Use tools like Google Tag Assistant or GA4's DebugView to troubleshoot any issues and verify proper implementation. 

13. Document configuration 

Document your GA4 setup, including tracking codes, data stream configurations, custom events, and any other relevant settings. This documentation serves as a reference for future maintenance and troubleshooting. 

14. Stay updated 

Keep up with new features, updates, and best practices for GA4 to optimise your tracking setup continually. Regularly review and refine your configuration based on evolving business needs and changes in the digital landscape. 

The limitations and challenges of GA4

While Google Analytics 4 (GA4) offers powerful features and capabilities for eCommerce businesses, there are several challenges and limitations that need to be considered during the implementation process. These challenges can impact data accuracy, continuity, and the overall effectiveness of the tracking setup. By understanding and addressing these potential roadblocks, businesses can make informed decisions and develop a robust data tracking strategy.


Defining goals & account setup 

Each business has unique data requirements, intricately linked to its goals, objectives, and nature. 

For GA4 implementation, constructing a robust data framework is imperative. This framework should facilitate cross-platform collaboration, ensuring data coherence and scalability. As the business expands, the architecture should flexibly accommodate alterations and additions to analytic needs, optimising resources. By adopting this approach, businesses streamline their strategies into a unified system, simplifying management. 

Data collection & Tracking 

Google Analytics 4 undoubtedly offers robust capabilities. However, like any tool, it has its limitations. Each feature has its constraints, and these limitations can substantially influence your tracking strategy, depending on your account type, whether free or paid.

Prior to delving into GA4 implementation, it's crucial to craft a data-tracking blueprint that empowers you and your team to make well-informed decisions. A robust data tracking plan can unveil growth opportunities and help you stay ahead of the competition. To achieve this: 

  1. Develop a comprehensive analytics strategy aligned with your business objectives. 

  2. Define clear Objectives and Key Results (OKRs) along with associated Key Performance Indicators (KPIs). 

  3. Establish a structured documentation system as a single source of truth. 

  4. Collaborate with the legal department to ensure adherence to data practices, laws, and regulations across different regions. 

  5. Compile a list of events requiring tracking, encompassing both client and server sides. 

  6. Specify the data to be collected in each event/touchpoint (dimensions). 

  7. Outline strategies for segmenting the data effectively 

  8. Setup multiple DataStreams for each platform 


GA4's events-based tracking system consolidates multiple data sources into one account, unlike Universal Analytics. It seamlessly integrates web and app data within the same account but requires careful consideration for smooth implementation. 

To streamline cross-referencing, it's advisable for GA4 to adopt standardised event names and parameters across various platforms. Often, organisations employ disparate naming conventions on different platforms, complicating data comparison.

Additional recommendations to simplify the process include: 

  • For websites without an app, adhere to standard web and GA4 recommended Events for naming and implementation in the app. 

  • Conversely, for apps like Firebase, utilize the sheet template to identify app events that can be linked to the web. Renaming web events via GTM is easier than altering hardcoded app events. 

  • Coordinate with both web and app development teams, ensuring consistency in capitalisation, such as Signup vs. signup. 

Multiple Firebase projects can’t be linked to one GA4 property 

It's important to note that when integrating Firebase with GA4, only one Firebase project can be linked to a single GA4 property. Therefore, if you have multiple Firebase projects, they must all be transferred to the same project, irrespective of the operating system used. 

This can be a challenging task and requires planning. Be mindful that you may encounter technical hurdles or limitations while consolidating all your Firebase projects into one. Prior to commencing, it's advisable to convene with your developers to comprehend the dependencies of each Firebase configuration. 


Different methods of data collection from GA4 

You have two options for transmitting information to GA4: you can send data directly from the client side (Web and App), or you can send all information to a server (Web and App) and then forward it from the server to GA4.

Data accuracy and troubleshooting 

After setting up your tracking foundation, it's imperative to engage a team of proficient data analysts to meticulously review the outcomes. Through the creation of comprehensive dashboards that consolidate all data into a central hub, they can promptly detect any anomalies and devise a strategic response. This methodology guarantees the ongoing effectiveness of your tracking endeavours and facilitates continuous process enhancement to maintain a competitive edge. 


Data continuity and historical comparisons 

Transitioning to GA4 presents challenges in maintaining data continuity and conducting historical comparisons. This is due to potential disparities in data models between GA4 and previous platforms like GA3. Consequently, historical data from the old platform may not be directly comparable, complicating trend analysis and historical data comparison. Three critical questions arise: 

  • How crucial is it for you to uphold data continuity and historical comparisons during the migration? 

  • What strategies can you deploy to bridge the gap between the Previous System and GA4 data for meaningful analysis? 

  • How can you ensure a seamless transition without sacrificing the ability to compare historical data? 

Your analytics plan should be tailored based on the insights gleaned from addressing these questions. 

Continue evolving with Google Analytics 4

By considering the technical implementation steps outlined in this article, eCommerce businesses can harness the full potential of GA4 to stay competitive in a rapidly evolving digital landscape.  

Metyis specialises in helping eCommerce businesses seamlessly implement Google Analytics 4 (GA4) to unlock the full potential of their data. We offer solutions tailored to the specific needs of the business, ensuring comprehensive event tracking, enhanced eCommerce integration, and cross-platform analysis.

Our team of experts guides clients through every step of the implementation process, from setting up GA4 properties to customising events and parameters, ultimately empowering businesses to make data-driven decisions, personalise experiences, improve customer satisfaction, and drive sustainable growth in the competitive eCommerce landscape. 

Our next article will uncover the post-implementation landscape of GA4 and offers insights into its impact on eCommerce business using best practices.


About the authors behind this article

Fabio Freitas is a performance marketing expert in Portugal office. He is a performance marketing expert well-versed in programming language skills, with a special focus in the fields of lead generation, and data & analytics. 

Akshay Singh is a Principal in the Amsterdam office. He has over a decade experience and spearheaded digital transformative initiatives in particularly within Fashion industry.