Matomo is web analytics built for organisations that need to own their visitor data. It has been developed in the open since 2007, and the self-hosted edition gives you the complete dataset in your own database, with no sampling, no third-party processing and no sharing arrangement to review with a lawyer. For public sector bodies, healthcare providers and European companies under GDPR scrutiny, that is frequently the only acceptable arrangement.
Functionally it covers the ground you expect: visits, sources, campaigns, goals, ecommerce, site search, custom dimensions and events. Beyond that it includes several things normally sold as separate products: heatmaps and session recordings, A/B testing, form analytics that show which field people abandon, a tag manager, and funnel analysis. Reports can be scheduled and emailed, and the whole thing is scriptable through a full HTTP API, so the numbers can feed a warehouse or an internal dashboard.
The privacy features are the substance rather than marketing. IP addresses can be anonymised, cookies can be switched off entirely while still producing usable reports, data retention can be enforced automatically, and visitors can be given an opt-out. Configured this way, Matomo is one of the few analytics tools that can be run without a consent banner in several jurisdictions, though this depends on your configuration and your regulator and should be checked rather than assumed.
The trade-offs are practical. Self-hosting means you are responsible for a PHP application and a MySQL or MariaDB database, and at high traffic that database needs care: archiving reports is the expensive operation and needs a cron job rather than on-demand processing. The interface is dense and looks like software designed by engineers, which it is. The cloud edition removes the operational burden and is priced per hit, which is competitive at modest volumes and less so at large ones.
Migration is genuinely supported: there is an importer for existing Google Analytics data, so switching does not mean discarding history, which removes the most common objection to moving.
Who it suits: organisations with legal or policy requirements about visitor data, and anyone who wants unsampled numbers they control. Who should look elsewhere: teams with no capacity to run a database, unless they take the cloud edition.