Mene
Privacy-first period tracking app with local-only data, zero cloud sync, bilingual (EN/RO).
The challenge
Period tracking apps collect sensitive health data and sync it to remote servers. Many users want cycle tracking without creating an account or trusting a third party with intimate health information. The app needed to deliver full functionality with zero network requests and encrypted local storage.
Architecture
What I built
Simple, intuitive period start and end date logging with flow intensity tracking. The interface prioritizes speed of entry so users can log in seconds, with the calendar providing immediate visual feedback of recorded cycles.
Algorithm-driven cycle and period predictions based on historical data using date-fns calculations. Predictions improve in accuracy as more cycles are logged, with clear visual distinction between recorded and predicted dates on the calendar.
Full-screen calendar with color-coded cycle phases, period days, and predicted windows. Built on react-native-calendars with custom day rendering that communicates cycle status at a glance without requiring users to tap into detail views.
Daily mood and symptom logging with predefined categories and optional notes. Data stays entirely on-device and can be reviewed alongside cycle data to help users identify recurring patterns across their menstrual cycles.
Local notification reminders for upcoming predicted periods, logging prompts, and custom alerts. All scheduling happens on-device using predicted dates, with no server component involved in notification delivery.
Zero-cloud architecture where all data lives in MMKV encrypted storage on the device. No accounts, no analytics, no telemetry, no network requests. Users own their data completely with no third-party access possible by design.