Mixpanel

What it does

Funnels, retention, and behavioral event tracking

Mixpanel tracks what users actually do inside a product or website, every click, page view, and custom-defined event, and lets a team build funnels and retention curves from that data.

It's mainly used by product and growth teams to answer behavioral questions a general web-analytics tool doesn't answer well: which specific in-product action correlates with retention, where in a signup flow people drop off, and whether a feature change actually moved the numbers. It also includes A/B testing and feature flag management.