Plethscape is a free interactive 3D simulator that models photoplethysmography (PPG) waveforms, letting users explore how pulse signals differ across seven wearable measurement sites, three light wavelengths (green, red, infrared), and varying physiological conditions like age, breathing, and movement.
It is most valuable when developing wearable or fitness apps that consume PPG sensor data, designing visualizations for biosignals, or prototyping interactive 3D educational content for the web.