OpenPPG vs Chimer

OpenPPG is a free, research-oriented iOS application designed to close the gap in accessible and transparent PPG data acquisition. Built by researchers for researchers, it enables recording of raw, high-quality photoplethysmography (PPG) signals directly from the smartphone camera, with full export for scientific analysis. Key Features • Raw signal access – capture unprocessed PPG waveforms with complete control over export (CSV format). • Flexible preprocessing – raw signals, basic and advanced filtering, signal quality assessment or fully calculated metrics in one app to enhance your research • Feature extraction – access directly over 11 automatically calculated temporal and morphological metrics without need for advanced signal processing • Metadata & annotations – mark events while taking measurements in real time and customise forms to fit your study protocol • Explainable pipeline – reproducible acquisition process with transparent documentation to ensure research reliability. Why OpenPPG? Most mobile tools restrict access to raw data, hide acquisition details, or require payment. OpenPPG removes these barriers by providing a free, standardised, and reproducible way to acquire PPG signals. It supports innovation in signal processing, machine learning, and digital biomarker discovery. Important: OpenPPG is intended solely for research purposes. It is not a medical device and must not be used for diagnosis, treatment, or patient self-monitoring.

Time-teller is a simple spoken time app for work, exercise, reading, studying, driving, or staying focused. Key features: • Automatic announcements every 1, 2, 3, 4, 5, 10, 15, 30, or 60 minutes • Custom intervals and exact-time announcements • Traditional Chinese and English voices • Background playback and Picture in Picture The free version only shows a banner ad at the bottom and does not interrupt operation. Make a one-time Remove Ads Forever purchase for a permanently ad-free experience. No subscription.