{"id":16330,"date":"2025-07-16T10:59:36","date_gmt":"2025-07-16T08:59:36","guid":{"rendered":"https:\/\/wearekemb.com\/?p=16330"},"modified":"2026-08-18T13:41:55","modified_gmt":"2026-08-18T13:41:55","slug":"comparing-ga4-piwik-pro-and-fathom-analytics","status":"publish","type":"post","link":"https:\/\/wearekemb.com\/en\/comparing-ga4-piwik-pro-and-fathom-analytics\/","title":{"rendered":"Comparing GA4, Piwik PRO, and Fathom Analytics: A data based analysis"},"content":{"rendered":"\n

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.<\/span><\/p>\n\n\n\n

That\u2019s why today we\u2019re taking a closer look at three different website analytics tools we\u2019ve used across various client projects\u2014and on our own site. While all three serve the same core purpose\u2014website analytics\u2014they each come with unique features, strengths, and limitations that make them better suited for certain use cases.<\/span><\/p>\n\n\n\n

From technical setup and attribution modeling to data privacy and compliance, every platform makes trade-offs.<\/span><\/p>\n\n\n\n

To help you make an informed decision, we\u2019ve prepared a side-by-side comparison covering one full month (June 1st to July 1st). This analysis highlights where each tool excels\u2014and where it falls short\u2014backed by real data and practical experience.<\/span><\/p>\n\n\n\n

GA4, Fathom, and Piwik PRO: distinct strengths and trade-offs<\/h2>\n\n\n\n

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.<\/span><\/p>\n\n\n\n

Google Analytics 4 (GA4)<\/h3>\n\n\n\n

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\u2019s 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.<\/span><\/p>\n\n\n\n

Fathom Analytics<\/h3>\n\n\n\n

Fathom takes a radically different approach: simplicity, speed, and privacy by default. Its clean interface and no-cookie policy appeal to users who don\u2019t need granular behavioral data but want a clear picture of their site\u2019s performance without legal headaches. However, the trade-off is that Fathom lacks advanced segmentation, event tracking details, and integrations that power users might expect. <\/span><\/p>\n\n\n\n

Piwik PRO Analytics Suite<\/h3>\n\n\n\n

 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\u2019s 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.<\/span><\/p>\n\n\n\n

GA4 vs. Piwik PRO vs. Fathom \u2013 Quick Feature Comparison<\/h2>\n\n\n\n
Feature<\/strong><\/th>Google Analytics 4<\/strong><\/th>Piwik Pro<\/strong><\/th>Fathom Analytics<\/strong><\/th><\/tr><\/thead>
Hosting Type<\/strong><\/td>Cloud only<\/td>Cloud & On-premise<\/td>Cloud only<\/td><\/tr>
GDPR Compliance<\/strong><\/td>Multi step process<\/td>Privacy focus<\/td>Privacy focus<\/td><\/tr>
Event Tracking<\/strong><\/td>Detailed<\/td>Detailed<\/td>Simple<\/td><\/tr>
Data Ownership<\/strong><\/td>Google owns<\/td>You own<\/td>You own<\/td><\/tr>
UI\/UX<\/strong><\/td>Steep learning curve<\/td>Moderate learning curve<\/td>very simple<\/td><\/tr>
Pricing<\/strong><\/td>Free and paid options<\/td>Very soon: paid only<\/td>Paid only<\/td><\/tr>
Integrations<\/strong><\/td>Deep (Ads, BigQuery, GSC,…)<\/td>Deep (Ads, GSC, PBI,…)<\/td>No integrations<\/td><\/tr>
Consent-free Tracking<\/strong><\/td>No<\/strong> – cookie dependent<\/td>Yes<\/strong> – anonymous tracking for non consenting users<\/td>Yes<\/strong> – cookie free tracking<\/td><\/tr>
Use Cases<\/strong><\/td>Experimenting + flexibility<\/td>Privacy + enterprise<\/td>Privacy + simplicity<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Sessions and views\u00a0<\/h2>\n\n\n\n

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.<\/span><\/p>\n\n\n\n

Google Analytics 4 (GA4)<\/h3>\n\n\n\n
    \n

  • Uses an \u201cengaged session\u201d model: triggered if a user stays for 10+ seconds, views 2+ pages, or fires a conversion<\/span><\/p><\/li>\n\n\n\n

  • Bounce rate is replaced with \u201cengagement rate.\u201d<\/span><\/p><\/li>\n\n\n\n

  • Sessions can extend past midnight and restart after 30 minutes of inactivity<\/span><\/p><\/li>\n<\/ul>\n\n\n\n

    Piwik PRO<\/h3>\n\n\n\n
      \n

    • Allows custom session timeout configuration<\/span><\/p><\/li>\n\n\n\n

    • Keeps the classic session definition from Universal Analytics<\/span><\/p><\/li>\n\n\n\n

    • Offers detailed session-level insights including session logs and dwell time<\/span><\/p><\/li>\n<\/ul>\n\n\n\n

      Fathom Analytics<\/h3>\n\n\n\n
        \n

      • Doesn’t use “sessions”; instead tracks \u201cvisitors\u201d per 24-hour window<\/span><\/p><\/li>\n\n\n\n

      • If a user visits multiple times in 24 hours, it still counts as one visitor<\/span><\/p><\/li>\n\n\n\n

      • No detailed session-level reporting<\/span><\/p><\/li>\n<\/ul>\n\n\n\n

        On this section we will only compare GA4 and Piwik Pro since Fathom does not have a quite similar measure.<\/span><\/p>\n\n\n\n

        The Data: Sessions<\/h3>\n\n\n\n
        \"Sessions<\/figure>\n\n\n\n

        Because <\/span>Piwik tracks users anonymously\u2014when there is no consent<\/b>\u2014it\u2019s no surprise that session counts are consistently higher compared to GA4. In contrast, <\/span>GA4 sessions are more stable<\/b>, showing smaller fluctuations, while <\/span>Piwik displays more steep spikes and drops<\/b>.<\/span><\/p>\n\n\n\n

        Although there is some <\/span>overlap in weekly trends<\/b>, 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.<\/span><\/p>\n\n\n\n

        The gap between the tools is significant. If you rely on analytics for <\/span>KPI tracking<\/b>, it\u2019s critical to acknowledge that <\/span>GA4\u2019s privacy-compliant setup limits data collection<\/b>\u2014potentially underrepresenting user behavior. Throughout most of our comparison period, <\/span>Piwik recorded nearly double the sessions<\/b>. That means <\/span>around half the audience not captured in GA4<\/b> may still carry valuable business insights\u2014insights we risk overlooking if we treat GA4 as the sole source of truth.<\/span><\/p>\n\n\n\n

        The Data: page views<\/h3>\n\n\n\n
        \"Page<\/figure>\n\n\n\n

        Piwik consistently reports the highest page views<\/b>, with visible spikes that tend to  exceed the other two tools. Because both Piwik and Fathom have set ups that allow to track non consenting users while respecting privacy and GDPR laws their behavior is very similar except for the date of 21 of june. <\/span><\/p>\n\n\n\n

        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. <\/span><\/p>\n\n\n\n

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

        Event Tracking<\/h2>\n\n\n\n

        GA4<\/h3>\n\n\n\n
          \n

        • Tracks many events automatically (scroll, outbound clicks, file downloads)<\/span><\/p><\/li>\n\n\n\n

        • Lets you define custom events with up to 25 parameters<\/span><\/p><\/li>\n\n\n\n

        • Conversion goals are event-based<\/span><\/p><\/li>\n<\/ul>\n\n\n\n

          Piwik PRO<\/h3>\n\n\n\n
            \n

          • It has some events tracked automatically ( including scroll and outbound clicks) <\/span><\/p><\/li>\n\n\n\n

          • Most of events have to be  manually defined but flexible<\/span><\/p><\/li>\n\n\n\n

          • Event tracking can be set up using Tag Manager or JavaScript<\/span><\/p><\/li>\n\n\n\n

          • Supports detailed goal tracking for any user action<\/span><\/p><\/li>\n<\/ul>\n\n\n\n

            Fathom Analytics<\/h3>\n\n\n\n
              \n

            • 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<\/span><\/p><\/li>\n\n\n\n

            • Tracks page views and simple goals (via URL visits or UTM campaigns)<\/span><\/p><\/li>\n\n\n\n

            • Minimal behavioral data is collected for privacy reasons<\/span><\/p><\/li>\n<\/ul>\n\n\n\n

              We did not compare event numbers across platforms, as <\/span>Fathom\u2019s event tracking is much simpler<\/b> and not directly comparable. However, from an implementation standpoint, having GA4 events already tracked via Google Tag Manager (GTM) proved beneficial\u2014<\/span>we were able to reuse existing triggers and variables<\/b> for the Piwik Pro setup, streamlining the process. <\/span><\/p>\n\n\n\n

              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.<\/span><\/p>\n\n\n\n

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

              For more advanced insights\u2014like <\/span>customer journey analysis, event flows, and funnel tracking<\/b>\u2014the 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.<\/span><\/p>\n\n\n\n

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

              In contrast, once event tracking is configured in Piwik, many <\/span>already existent reports<\/b> offer a comprehensive and intuitive view of user interactions\u2014making it more accessible for non-technical teams.<\/span><\/p>\n\n\n\n

              Attribution<\/h2>\n\n\n\n

              GA4<\/h3>\n\n\n\n
                \n

              • Offers basic attribution models like last-click and data-driven<\/span><\/p><\/li>\n\n\n\n

              • Multi-channel funnel reports are limited in the standard version<\/span><\/p><\/li>\n\n\n\n

              • Lookback windows are customizable for <\/span>longer customer journeys<\/b> or <\/span>multi-touch attribution needs<\/b><\/p><\/li>\n<\/ul>\n\n\n\n

                Piwik PRO<\/h3>\n\n\n\n
                  \n

                • Provides multiple attribution models: first-click, last-click, linear, time decay, position-based<\/span><\/p><\/li>\n\n\n\n

                • Allows full multi-touch path analysis<\/span><\/p><\/li>\n\n\n\n

                • Lookback windows are configurable to fit your sales cycle<\/span><\/p><\/li>\n<\/ul>\n\n\n\n

                  Fathom Analytics<\/h3>\n\n\n\n
                    \n

                  • Uses a basic \u201cfirst pageview\u201d attribution model<\/span><\/p><\/li>\n\n\n\n

                  • No multi-touch attribution or advanced modeling<\/span><\/p><\/li>\n\n\n\n

                  • Good for quick insights but not suitable for campaign-level analysis.<\/span><\/p><\/li>\n<\/ul>\n\n\n\n

                    \"Sessions<\/figure>\n\n\n\n

                    Across all three platforms, <\/span>Organic Search is the dominant traffic source<\/b>, with only slight differences in attribution. GA4 reports 65.5%, Fathom closely follows with 64.4%, and Piwik attributes 54.3% to Organic Search. While the overall consistency suggests reliable recognition of search engine traffic, Piwik’s noticeably lower percentage may indicate that some of this traffic is being misattributed, possibly to Direct or other channels.<\/span><\/p>\n\n\n\n

                    Direct traffic appears as the second-largest source<\/b> 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.<\/span><\/p>\n\n\n\n

                    When it comes to<\/span> Paid Search<\/b>, 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\u2019s 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.<\/span><\/p>\n\n\n\n

                    When looking at <\/span>Referral traffic<\/b>, 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.<\/span><\/p>\n\n\n\n

                    Unassigned traffic<\/b> 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.<\/span><\/p>\n\n\n\n

                    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.<\/span><\/p>\n\n\n\n

                    Privacy and Data Ownership<\/h2>\n\n\n\n

                    GA4<\/h3>\n\n\n\n
                      \n

                    • Requires cookie consent to comply with GDPR\/CCPA<\/span><\/p><\/li>\n\n\n\n

                    • Partial IP anonymization is offered, but Google hosts and processes the data<\/span><\/p><\/li>\n\n\n\n

                    • Data often stored in the US, which may present regulatory concerns<\/span><\/p><\/li>\n<\/ul>\n\n\n\n

                      Piwik PRO<\/h3>\n\n\n\n
                        \n

                      • Fully GDPR and HIPAA compliant<\/span><\/p><\/li>\n\n\n\n

                      • You own the data and can choose EU-based or private cloud hosting<\/span><\/p><\/li>\n\n\n\n

                      • Option for self-hosting in enterprise setups<\/span><\/p><\/li>\n<\/ul>\n\n\n\n

                        Fathom Analytics<\/h3>\n\n\n\n
                          \n

                        • Cookie-free and GDPR-compliant by default<\/span><\/p><\/li>\n\n\n\n

                        • Does not store personal data or track individuals across sessions<\/span><\/p><\/li>\n\n\n\n

                        • Hosted in EU or US depending on your choice, but with a privacy-first design<\/span><\/p><\/li>\n<\/ul>\n\n\n\n

                          When it comes to implementation, both <\/span>GA4 and Piwik Pro require integration with a cookie consent banner<\/b> 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 <\/span>comprehensive and well-structured documentation<\/b>. Additionally, <\/span>Piwik Pro offers a built-in Consent Manager module<\/b>, which makes it possible to manage user permissions directly within the platform\u2014streamlining the integration process and reducing reliance on third-party tools.<\/span><\/p>\n\n\n\n

                          On the other hand, <\/span>Fathom positions itself as a privacy-focused analytics solution that does not require a cookie banner<\/b> under most use cases, as it does not track personal data or set cookies by default. However, it\u2019s important to note that in most real-world scenarios, a website likely uses other tools\u2014such as advertising platforms\u2014that do require consent. In those cases, <\/span>a cookie management system might still be necessary<\/b>, even if the analytics tool itself is exempt.<\/span><\/p>\n\n\n\n

                          From our experience, one of the most valuable aspects of using Piwik Pro is the ability to <\/span>link consent status directly to behavioral data<\/b>. 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.<\/span><\/p>\n\n\n\n

                          Usability<\/h2>\n\n\n\n

                          GA4<\/h3>\n\n\n\n