PostHog

PostHog is an open-source product analytics platform that bundles behavior analysis, session replay and feature flags into a single tool.

Its strength is breadth on one dataset: the same event stream feeds the charts, the recordings and the flag targeting, so a drop at a funnel step can be followed straight into recordings of the users who dropped. Autocapture is on by default and records clicks and pageviews without manual instrumentation, which makes the start fast and later leaves a noisy event list that still consumes volume. The phrase open-source needs a qualifier here: most of the repository is MIT licensed but the enterprise directory is not, and the practical route today is the hosted cloud rather than a supported self-hosted install.