PostHog is a product analytics platform. It bundles product analytics, web analytics, session replay and heatmaps, feature flags, experiments, surveys, error tracking and a data warehouse in one product. PostHog is open source: the repository is MIT-licensed, except for the ee directory, which has its own licence. You can use PostHog Cloud, with a choice between an EU and a US region, or host the software yourself using Docker.
According to a company directory, PostHog is based in San Francisco, in the United States. In PostHog Cloud EU, data runs on servers in Frankfurt, which the vendor recommends for GDPR compliance; IP address capture is off by default for new projects there. With self-hosting you control the location yourself and are both data controller and processor, but PostHog provides no support or guarantees for self-hosted installations. The US headquarters remains relevant to the question of which law applies to the cloud service.