PostHog

PostHog is an open-source product analytics platform that bundles event tracking, session replay, feature flags, A/B testing, and surveys into a single tool, aimed at engineering-led product teams who want to instrument their own analytics rather than hand data to a third-party SaaS. Because it can be self-hosted or run as a managed cloud service, teams with strict data residency or privacy requirements can keep raw user data inside their own infrastructure while still getting the same product analytics workflows as hosted competitors. PostHog's event pipeline captures user behavior across web and mobile apps, and its session replay feature lets product teams watch real user sessions to understand exactly where users get stuck, which is often more actionable than a funnel chart alone. Feature flags and experimentation tools are built into the same product, so a team can ship a feature behind a flag, roll it out gradually, and measure its impact on retention or conversion without stitching together three separate vendors. SQL-based insights and a data warehouse integration let more technical teams query raw event data directly when the built-in dashboards aren't enough. PostHog is popular with early-stage and growth-stage startups specifically because its generous free tier and transparent usage-based pricing let a team start instrumenting analytics before they have meaningful revenue to spend on tooling.