Nila

Nila is a privacy-first menstrual cycle tracking PWA for iPhone and iPad. Given what period-tracking data has been used for, the design starts from a hard constraint: the server must never be able to read a single health detail — not a period date, not a symptom, not a mood, not a note.

Zero-knowledge by construction

The master key is derived from your password with PBKDF2 (600k iterations) and never leaves the device. Every cycle and daily log is AES-256-GCM encrypted client-side; the server stores only a random UUID and an encrypted blob, plus the PBKDF2 salt and a wrapped master key. A 12-word BIP39 recovery phrase covers account recovery without the password, and the same password unlocks the same data across iPhone and iPad. “We don’t look at your data” is a promise; the server structurally cannot is an architecture — Nila is the second.

The tracking itself

Four-phase cycle model (period, follicular, ovulation, luteal) with confidence-weighted prediction from your history, and a five-state period status (none, approaching, late, active-started-today, active-ongoing) that each gets its own home-screen treatment. Predictions recalculate automatically whenever cycles are added, edited, ended, or removed. Daily check-ins (mood, energy, flow, symptoms, notes) feed pattern-aware insight cards — “you tend to log cramps in your luteal phase” — plus a scrubable hormone graph and phase-aware food/movement recommendations.

Built on Next.js 16 (App Router) + TypeScript, Tailwind v4 and Framer Motion, Supabase for auth and encrypted storage only, and the @noble / @scure libraries for the crypto. Installable, offline-capable, dark/light/system theme that syncs across devices, with iOS push for period reminders.