Amplitude is the established heavyweight in product analytics: event-based tracking with funnels, retention curves, cohort analysis and behavioral segmentation, plus experimentation, feature flags and session replay in the same suite. Its governance tooling keeps large event taxonomies sane.
It suits product organizations making roadmap decisions from behavioral data. The free Starter tier gets teams going, but real deployments should expect enterprise-style sales and pricing — the point where engineering-led teams often evaluate PostHog.