BioDecay is a high-precision pharmacokinetic modeling engine for iOS. Using dynamic compartmental models, it visualizes in real time how hydration, caffeine, and key supplements interact within your physiology. The app is free to use for hydration and caffeine tracking. A single in-app purchase unlocks advanced modeling and curves for protein, creatine, and magnesium. Features include real-time metabolic curves, dynamic bio-interactions, and PDF reporting.