Hey Product Hunt! 👋 I'm David, a solo dev from Taiwan. I built Correlate because I was paying $239/year for WHOOP when my Apple Watch already collects the same raw data. What was missing was the analysis layer. The feature I'm most proud of is Granger Causality Analysis — a real econometrics method that tests whether changes in one metric PREDICT future changes in another. It's the difference between "steps and sleep correlate" and "2,000 more steps today predicts 15 min more deep sleep tomorrow." Another one: Change Point Detection (AMOC algorithm) finds the exact date something shifted. Start a new supplement? It'll show you if your HRV actually changed — with statistical proof. I'd love to hear: - What health connections would you want to discover? - Is the free tier generous enough? Thanks for checking it out!