GA4 vs Piwik PRO vs Sealmetrics: Which One Fits an EU Marketing Team

When a European marketing team starts looking beyond GA4, the shortlist usually has Piwik PRO on it, and more often now a cookieless option. Comparing them feature by feature is where the evaluation goes wrong: the three products make different architectural choices, and those choices decide what each one can report long before any feature list does.

A declaration of interest: we make one of the three. The point of this piece is to be useful even if you do not choose us, so every competitor fact below comes from the vendor's own documentation, is dated, and ends with where each product is the better choice. The two-way comparisons go deeper: Sealmetrics vs GA4 and Sealmetrics vs Piwik PRO.

The comparison, side by side

Competitor facts checked against vendor documentation on 14 September 2026; tracker weights measured on 27 August 2026. Vendors change plans and defaults, so re-check before you sign.

The row that decides most evaluations: a visitor who says no

GA4 hands the decision to Consent Mode. In basic mode, a refusal sends nothing. In advanced mode, the tags send cookieless pings and GA4 models users and sessions, but only for properties above 1,000 denied events a day and 1,000 consented daily users, and the modelled data does not reach the BigQuery export. On Incapto's Shopify store, GA4 with Consent Mode did not record 29% of visits or 45% of pageviews over 48 days, and paid campaigns fell from 62% of traffic measured without consent loss to 50% in GA4.

Piwik PRO lets you decide how much identification to keep. With visitor cookies, it recognises returning visitors and offers several attribution models. With only the session hash, which lasts 30 minutes after the last event, it groups a visit and attributes by last click. With neither, Piwik PRO's help centre says each event is treated as a new session, returning visitors cannot be recognised and the data becomes less accurate. We have not run Piwik PRO side by side on a client site, so we publish no percentage for it; test the configuration you would deploy.

Sealmetrics has no such setting, because it has no identifier to switch off. It stores nothing on the device, groups a visit with a short-lived marker that is not kept in the browser, and credits each conversion to the source of the session in which it happens. The visitor who rejects the banner is measured the same way as the one who accepts it. Whether analytics without cookies is exempt from consent in your market still depends on your configuration and your national authority.

Where GA4 is the right choice

• Google Ads is the centre of your acquisition. Audiences, conversion import and bidding are native, and GA4 is the conduit many teams keep for them.
• Budget is tight. Standard GA4 costs nothing to license, and its ecosystem of integrations and people who know it is the largest.
• You need user-level analysis on consenting traffic. Cohorts, retention and paths are available where users accept cookies.

Where Piwik PRO is the right choice

• You want one vendor for the whole layer. Analytics, tag manager, consent manager and data activation come in the same contract.
• You need visitor-level analysis with privacy controls. With the identifiers enabled and a legal basis in place, it offers visitor continuity and several attribution models, and you choose the trade-off per site.
• Data location is a procurement requirement. It offers several public cloud regions and, on Enterprise, private cloud.

Where Sealmetrics is the right choice

• The decision is budget between channels and campaigns. Revenue by channel, campaign and creative, credited without consent loss, and checkable against orders.
• You do not want to govern an identifier configuration. There is no privacy mode to choose per site, because there is nothing to identify.
• Page weight matters. The tracker is about 1.1 KB on the wire.

What Sealmetrics does not do

It has no user-level analysis, cohorts, retention reports or cross-session journeys; no multi-touch or data-driven attribution; no tag manager, consent manager or activation module; and it does not send conversions to ad platforms, so GA4 or the platform pixels keep that job. If any of those is the main requirement, one of the other two is the better fit. The reasoning behind last click only is in last-click vs modelled attribution.

How to evaluate the three without trusting any vendor

1. Write down the decisions. Budget between channels, bidding, user-level product analysis and compliance evidence need different tools.
2. Configure each candidate as you would deploy it. For Piwik PRO, that means the identifier mode your legal team would approve, not the richest one.
3. Run them on the same site over the same weeks. A full commercial cycle; Incapto's comparison covered 48 days.
4. Reconcile each against real orders first. A tool that cannot match the order total is not a reference for channels. The method is in one number for marketing and finance.
5. Then compare the channel split and the work it took. Which reports survived your configuration, and how much governance each one needs.