For the current business framework using data for monitoring, decision making and productivity is a must. Online, even the smallest detail can make or break your business performance. But when it comes to analytics, there is no one-size-fits-all solution. The right tool depends heavily on your industry, revenue scale, and the complexity of your processes.

That’s why today we’re taking a closer look at three different website analytics tools we’ve used across various client projects—and on our own site. While all three serve the same core purpose—website analytics—they each come with unique features, strengths, and limitations that make them better suited for certain use cases.

From technical setup and attribution modeling to data privacy and compliance, every platform makes trade-offs.

To help you make an informed decision, we’ve prepared a side-by-side comparison covering one full month (June 1st to July 1st). This analysis highlights where each tool excels—and where it falls short—backed by real data and practical experience.

GA4, Fathom, and Piwik PRO: distinct strengths and trade-offs

From technical setup and attribution modeling to data privacy and compliance, every platform makes trade-offs.  Whether you prioritize deep insights, privacy, or control over your data, GA4, Fathom, and Piwik PRO each offer distinct strengths and trade-offs worth considering.

Google Analytics 4 (GA4)

GA4 is  attempting to modernize web and app analytics for a world where user privacy, mobile traffic, and AI-driven insights are increasingly important. It offers powerful features like cross-platform tracking, machine learning predictions, and deep integration with Google’s ad ecosystem that distinguish it among the analytics tools. The steep learning curve, complex setup, and opaque data sampling can frustrate users. To have a GDPR set up GA4 needs some technical set up to make sure consent signals are correctly set up and respected.

Fathom Analytics

Fathom takes a radically different approach: simplicity, speed, and privacy by default. Its clean interface and no-cookie policy appeal to users who don’t need granular behavioral data but want a clear picture of their site’s performance without legal headaches. However, the trade-off is that Fathom lacks advanced segmentation, event tracking details, and integrations that power users might expect. 

Piwik PRO Analytics Suite

 Piwik PRO offers the depth and flexibility of traditional enterprise analytics tools with a strong emphasis on compliance and data ownership. It supports both cloud and on-premise deployment, making it a top choice for regulated industries. Its interface is more intuitive than GA4’s and offers many features (like tag management and raw data export) out of the box. That said, it’s less plug-and-play than tools like Fathom, and some advanced features may require technical support or a paid plan. A strong contender for organizations that need robust analytics without compromising on data governance.

GA4 vs. Piwik PRO vs. Fathom – Quick Feature Comparison

Sessions and views 

It is important to know that each platform has different definitions, time frames and logics for the same measure. Sometimes they do not share a one to one match and so we will describe shortly how each platform looks at a measure and how we compared it.

Google Analytics 4 (GA4)

• Uses an “engaged session” model: triggered if a user stays for 10+ seconds, views 2+ pages, or fires a conversion

• Bounce rate is replaced with “engagement rate.”

• Sessions can extend past midnight and restart after 30 minutes of inactivity

Piwik PRO

• Allows custom session timeout configuration

• Keeps the classic session definition from Universal Analytics

• Offers detailed session-level insights including session logs and dwell time

Fathom Analytics

• Doesn’t use “sessions”; instead tracks “visitors” per 24-hour window

• If a user visits multiple times in 24 hours, it still counts as one visitor

• No detailed session-level reporting

On this section we will only compare GA4 and Piwik Pro since Fathom does not have a quite similar measure.

The Data: Sessions

Although there is some overlap in weekly trends, the correlation between the two tools is weak. A clear weekly pattern emerges: lower sessions on weekends and higher activity during weekdays. However, even on weekdays, the alignment between GA4 and Piwik is inconsistent.

The gap between the tools is significant. If you rely on analytics for KPI tracking, it’s critical to acknowledge that GA4’s privacy-compliant setup limits data collection—potentially underrepresenting user behavior. Throughout most of our comparison period, Piwik recorded nearly double the sessions. That means around half the audience not captured in GA4 may still carry valuable business insights—insights we risk overlooking if we treat GA4 as the sole source of truth.

The Data: page views

On Piwik this behaviour is due to one single user and session that had many page views events. The detailed session log allows us to see a user that was very engaged in our website and to understand better if it was a regular user or a bot. Whereas for Fathom the lack of data does not allow to go into detail for debugging. 

Nonetheless Fathom and Piwik follow a similar trend for most of the period, suggesting that both tools might use a comparable method for counting page views.  GA4 shows significantly lower page views throughout the timeline, rarely exceeding 70.

Event Tracking

GA4

• Tracks many events automatically (scroll, outbound clicks, file downloads)

• Lets you define custom events with up to 25 parameters

• Conversion goals are event-based

Piwik PRO

• It has some events tracked automatically ( including scroll and outbound clicks) 

• Most of events have to be  manually defined but flexible

• Event tracking can be set up using Tag Manager or JavaScript

• Supports detailed goal tracking for any user action

Fathom Analytics

• The event tracking is quite basic and one may track an event and its respective value but there is no event parameters to give further details

• Tracks page views and simple goals (via URL visits or UTM campaigns)

• Minimal behavioral data is collected for privacy reasons

We did not compare event numbers across platforms, as Fathom’s event tracking is much simpler and not directly comparable. However, from an implementation standpoint, having GA4 events already tracked via Google Tag Manager (GTM) proved beneficial—we were able to reuse existing triggers and variables for the Piwik Pro setup, streamlining the process.

Piwik also has a Tag Manager module that one can use. It is simple to set up and if there is previous knowledge of google tag manager a lot of the processes work similarly.

Fathom is ideal for users who want to monitor high-level metrics such as visits, visitors, bounce rate, and time on site, but it lacks the depth needed to analyze detailed user behavior.

For more advanced insights—like customer journey analysis, event flows, and funnel tracking—the relevant comparison lies between GA4 and Piwik. Fathom allows for event tracking but it focus more on the event count and conversion rate then on the behaviour itself.

In our experience, Piwik offers rich event-level detail and a user-friendly interface that delivers similar capabilities to GA4. GA4 provides for a lot of flexibility, this comes with a steeper learning curve, especially for those responsible for setup and maintenance.

In contrast, once event tracking is configured in Piwik, many already existent reports offer a comprehensive and intuitive view of user interactions—making it more accessible for non-technical teams.

Attribution

GA4

• Offers basic attribution models like last-click and data-driven

• Multi-channel funnel reports are limited in the standard version

• Lookback windows are customizable for longer customer journeys or multi-touch attribution needs

Piwik PRO

• Provides multiple attribution models: first-click, last-click, linear, time decay, position-based

• Allows full multi-touch path analysis

• Lookback windows are configurable to fit your sales cycle

Fathom Analytics

• Uses a basic “first pageview” attribution model

• No multi-touch attribution or advanced modeling

• Good for quick insights but not suitable for campaign-level analysis.

Direct traffic appears as the second-largest source across all tools, but with significant discrepancies. Piwik attributes around 33.2% of sessions to Direct traffic, and Fathom shows a similar figure at 32.5%, both considerably higher than GA4’s 20.9%. This gap suggests that both Piwik and Fathom may be over-reporting Direct traffic, especially in cases where UTM parameters are missing or consent settings prevent the collection of referrer information. In contrast, GA4 applies stricter rules to categorize traffic, reducing inflation in the Direct category.

When it comes to Paid Search, GA4 reports that 5.5% of sessions originate from paid campaigns. Piwik closely mirrors this with 5.2%, while Fathom reports only 2.1%. This notable difference in Fathom’s attribution could result from a different reporting period, incomplete or inconsistent UTM tagging, or even misclassification of paid campaigns under other traffic sources like Direct or Organic.

When looking at Referral traffic, both GA4 and Piwik show very similar attribution levels, with GA4 at 6.1% and Piwik at 6.4%, indicating that both platforms are effectively capturing traffic from external websites. Fathom, however, does not report Referral traffic at all, which either points to a limitation in its reporting scope or a simplification that rolls this traffic into another category, most likely Direct.

Unassigned traffic is reported exclusively in GA4, at around 1.4%. This category typically includes sessions where the source or medium is missing or uncategorized. Neither Piwik nor Fathom display this category explicitly, which suggests that they may drop such data or automatically group it under Direct, contributing further to the inflated Direct percentages observed on those platforms.

Additionally, external factors like ad blockers or cookie consent mechanisms may prevent certain scripts from loading or identifying users correctly, further impacting the accuracy of traffic categorization across tools.

Privacy and Data Ownership

GA4

• Requires cookie consent to comply with GDPR/CCPA

• Partial IP anonymization is offered, but Google hosts and processes the data

• Data often stored in the US, which may present regulatory concerns

Piwik PRO

• Fully GDPR and HIPAA compliant

• You own the data and can choose EU-based or private cloud hosting

• Option for self-hosting in enterprise setups

Fathom Analytics

• Cookie-free and GDPR-compliant by default

• Does not store personal data or track individuals across sessions

• Hosted in EU or US depending on your choice, but with a privacy-first design

When it comes to implementation, both GA4 and Piwik Pro require integration with a cookie consent banner to ensure GDPR compliance. In the case of Piwik Pro, connecting it with an external consent management platform may require a bit more technical effort compared to GA4, but this is well supported by comprehensive and well-structured documentation. Additionally, Piwik Pro offers a built-in Consent Manager module, which makes it possible to manage user permissions directly within the platform—streamlining the integration process and reducing reliance on third-party tools.

On the other hand, Fathom positions itself as a privacy-focused analytics solution that does not require a cookie banner under most use cases, as it does not track personal data or set cookies by default. However, it’s important to note that in most real-world scenarios, a website likely uses other tools—such as advertising platforms—that do require consent. In those cases, a cookie management system might still be necessary, even if the analytics tool itself is exempt.

From our experience, one of the most valuable aspects of using Piwik Pro is the ability to link consent status directly to behavioral data. This allows us to clearly distinguish between users who have given consent and those who haven’t, offering more transparency and control in our reporting. The combination of native consent management and robust behavioral analytics makes Piwik Pro a powerful option for organizations that need both compliance and depth in their data.

Usability

GA4

• Steeper learning curve due to flexible but complex interface

• The community and resources available are a plus

Piwik PRO

• Intuitive interface, similar to Universal Analytics

• Easier for traditional analysts to adopt. If you have experience with other tools the change into Piwik is very smooth

Fathom Analytics

• Super clean, minimal interface

• Very easy to set up and read the data

Reporting

GA4

• Offers customizable dashboards and “Exploration” tools

• Deep integration with BigQuery and Google Ads

• Most reporting tools can be integrated with GA4 which increases the flexibility

Piwik PRO

• Intuitive interface, similar to Universal Analytics

• Supports custom dashboards, goals, segments, and funnels

• A lot of the standard reports already give a very detailed overview

• Integration with tools such as GSC provide very insightful reports

Fathom Analytics

• Only core metrics: visitors, pageviews, bounce rate, time on site, and goals

• No segmentation or funnel analysis; designed for simplicity

As mentioned earlier, for users with simpler analytics needs—such as tracking basic metrics like visits, time spent on site, and bounce rate—Fathom is a strong choice. Its interface is designed for clarity and ease of use, allowing users to quickly access the most important numbers without the need to navigate through complex configurations or reports.

However, for those who require more in-depth analysis, the decision typically comes down to GA4 and Piwik Pro, as both platforms offer advanced capabilities. In our experience, GA4 provides extensive flexibility through its custom report builder, which is particularly valuable when testing new ideas or experimenting with different data views. It’s a powerful feature set for users who want to tailor their reporting to very specific use cases.

That said, Piwik Pro has impressed us with the depth and quality of its standard reports. Without needing much customization, it already delivers a highly detailed view of user behavior, funnels, and goal tracking. For teams that prefer structured insights right out of the box, this can be a significant advantage, reducing setup time while still offering actionable data.

Pricing Overview

GA4

• Free for most use cases

• Enterprise version (GA360) offers BigQuery export and advanced modeling, at a high cost

Piwik PRO

• Free Core version available for basic analytics. This will soon seize to exist

• Upcoming Business Plan  mimics core functionalities at a monthly subscription

• Enterprise plans with full features require a custom quote

Fathom Analytics

• Paid only; starts around $14/month based on traffic volume

• One price includes all features—no upsells or tiers

Until now, Piwik Pro’s free plan has been a major advantage, especially for teams working with limited budgets. It allowed users to access a comprehensive view of the user journey—including advanced reporting, event tracking, funnels, and consent management—without sacrificing data visibility or feature depth. This made it a compelling choice for organizations that needed powerful analytics capabilities without the financial commitment of enterprise tools.

However, with the upcoming changes to Piwik’s pricing model, where access to core features may now require a paid plan, the decision to use Piwik will likely become more budget-dependent. Teams will need to weigh the value of Piwik’s built-in features and strong privacy framework against the cost, and assess whether those capabilities justify the investment compared to other tools—particularly for those who previously relied on the free tier.

Ultimately, the choice may come down to how critical those advanced analytics features are to your workflow, and what level of financial flexibility your organization has when it comes to tracking and reporting infrastructure.

Which Tool Should You Choose?

Choose GA4 if you need robust behavioral analytics, detailed ad performance tracking, and integrations with tools like BigQuery. GA4 is ideal for teams that want to work with a flexible, event-based data model and are comfortable navigating a steeper learning curve in exchange for powerful customization and experimentation options. Use it knowing that it does not show 100% of what is happening on your website but it can be very useful to spot trends and monitor experiences.

Choose Piwik PRO if your organization operates in regulated industries—such as healthcare, finance, or handles EU client data—and you need full control over data privacy, hosting, and consent management. It’s a strong fit for teams that value data ownership, configurable reporting, and a solid balance between functionality and compliance.

Choose Fathom Analytics if simplicity and privacy are your top priorities. It’s perfect for blogs, portfolios, or smaller websites where quick access to core metrics like visits, time on site, and bounce rate is enough. Fathom removes complexity, offering a clean and fast way to understand your traffic without the overhead of deeper funnel or user-level analysis.

Conclusion

Our favorite platform often depends on the client’s goals, budget, and compliance requirements. GDPR and data protection concerns increasingly shape the way we approach analytics implementation, and we continue to explore all three platforms to understand their unique strengths. In many cases, insights gained from one tool can be applied to another, helping us refine and adjust our strategies as business needs evolve. By staying flexible and tool-agnostic, we’re better equipped to recommend the right setup—whether it’s for performance marketing, privacy-first operations, or anything in between. If you are still looking for the ideal solution yourself, feel free to reach out!