Fathom Analytics is an open source platform that provides simple, useful websites stats without tracking or storing personal data of your users. Fathom tracks users on a website (without collecting personal data) and gives you a breakdown of your top content and top referrers. It does so with user-centric rights and privacy, and without selling, sharing or giving away the data you collect.
Matomo (formerly Piwik) is an open source Google Analytics alternative that gives you full control over your data and protects user privacy
Plausible is an open-source, lightweight web analytics tool. Your website data is 100% yours and the privacy of your visitors is respected.
PostHog provides open-source product analytics, built for developers. It helps engineers understand their product usage, automate events, and user data collection.
Countly is an open source analytics platform to understand and enhance customer journeys in web, desktop and mobile applications.