PostHog

PostHog is an open-source platform built for product engineers who need to understand how their products perform. It brings together product analytics, session replay, feature flags, A/B testing, error tracking, surveys, and LLM observability into one toolkit, so you can avoid juggling multiple disconnected services.

The platform supports both cloud-hosted and self-hosted deployments. The self-hosted option uses ClickHouse as its primary data store, which handles large event volumes well. You can instrument events manually or use autocapture to start collecting data without writing tracking code for every interaction.

PostHog includes a natural language querying feature called PostHog AI that lets you ask questions about your product data in plain English. It also offers LLM analytics for tracking AI feature usage, cost, and performance inside your own applications. The free tier covers up to one million events per month, with usage-based pricing scaling from there.