PostHog

PostHog is an all-in-one, open-source developer platform that bundles product analytics, web analytics, session replay, feature flags, A/B testing, experiments, surveys, error tracking, a customer data platform, and a data warehouse into a single stack engineers can self-host or run in the cloud. Founded in 2020 by James Hawkins and Tim Glaser through Y Combinator, it lets product engineers track usage, ship features, and keep customer data in one place rather than stitching together a dozen SaaS tools. The company reached unicorn status in 2025 with a $75M Series E at a $1.4B valuation.