Harmony – Cycle & Partner Care

Private, multilingual cycle and pregnancy tracking with secure cloud backup, partner sharing, smart insights, reminders, and an Android-first experience.

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Inspiration

Harmony was created to make cycle and pregnancy care private, understandable, and supportive for people everywhere—not limited to one country or language. The goal is a calm, accessible space for daily tracking, meaningful insights, and optional partner support.

Across every product I build, the starting point is the same: make everyday life easier through a level of simplicity I often cannot find in comparable apps. I developed Harmony while managing multiple chronic health conditions, and that experience made low-friction flows, calm visuals, clear language, and accessibility especially important—the app should reduce effort, not add another burden.

What it does

  • Tracks periods, symptoms, fertility windows, pregnancy progress, water, weight, and private notes
  • Supports English, Turkish, German, Spanish, French, Italian, Portuguese, and Russian
  • Works local-first, with optional Google sign-in and secure cloud backup and restore
  • Connects partners through an invite code and shares only the insights the user allows
  • Gives the connected partner useful cycle, symptom, wellness, and pregnancy context
  • Sends reminders and privacy-safe partner update notifications
  • Provides an Android-first mobile experience with biometric protection and device integrations

How we built it

Harmony uses React, TypeScript, Vite, Tailwind CSS, and Capacitor. Supabase provides Google authentication, PostgreSQL, Row Level Security, Realtime-ready data access, and Edge Functions. Firebase Cloud Messaging delivers partner notifications through a least-privilege service account. Native Android integrations handle notifications, biometrics, sharing, file operations, and device-safe storage.

During OpenAI Build Week, Codex with GPT-5.6 helped map and audit the existing codebase, improve onboarding and Google sign-in, redesign partner mode, implement secure synchronization and push delivery, refresh Android assets, and verify production and Gradle builds.

Challenges we ran into

The hardest challenge was balancing useful partner insights with sensitive health-data privacy. We designed server-only device-token storage, JWT-protected functions, Row Level Security policies, idempotent notification delivery, generic lock-screen copy, and automatic retry without exposing raw health data.

Accomplishments that we're proud of

We delivered a multilingual, local-first product with optional cloud continuity, fast Google authentication, partner connection flows, secure RLS-backed access, privacy-aware notifications, and a working Android APK.

What we learned

Privacy and usability work best when they are designed together. A global health app also needs language support and neutral product language from the beginning—not as an afterthought.

What's next for Harmony

Native iOS packaging, Apple sign-in, richer consent controls, expanded partner education, accessibility improvements, and more personalized—but still privacy-preserving—insights.

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