Caffeine Health — Open Source Fitness App

Caffeine Health is a beautifully designed Android app that helps you understand how your caffeine intake affects your body throughout the day — and whether that late-afternoon espresso might cost you sleep tonight. Log drinks from a curated catalog, watch your active caffeine level in real time on a 24-hour curve, and get a personalized sleep forecast based on your unique metabolism. Features: • Real-time 24-hour caffeine curve with emoji drink markers • Personalized pharmacokinetic modeling based on age, weight, lifestyle • Sleep forecast — see if caffeine will affect your bedtime • Curated drink catalog: coffee, tea, energy drinks, soda • Drink detail sheets showing individual contribution curves • Quick actions — edit, duplicate, or delete entries • Material 3 Expressive design with dynamic color • Montserrat typography and haptic feedback throughout • Full dark mode support Privacy: • Fully offline — all data stays on your device • No ads, no tracking, no analytics, no accounts • Open source (GPL-3.0) Science: The app uses a one-compartment oral pharmacokinetic model with personalized half-life calculation. Your caffeine metabolism is estimated from age, weight, smoking status, alcohol intake, and CYP1A2-inhibiting medications — grounded in real pharmacology.