Vellum: Period Tracker

Vellum is a quiet, private almanac for your menstrual cycle.

Estimates only - not medical advice, not a contraceptive.

Log periods, symptoms, mood, sleep, basal body temperature, and notes in a local database on your device. Vellum has no sign-in, no accounts, no cloud sync, no analytics SDK, no crash reporter, and no ads. Your cycle data stays on your device unless you choose to export or share a backup.

WHAT YOU CAN LOG
- Flow level, symptoms, mood, energy, sleep hours
- Sexual activity, discharge, medications, free-text notes
- Basal body temperature in C or F

WHAT YOU SEE
- Today screen with an interactive ring showing the selected cycle day and estimated phase
- Month calendar with logged days and clearly marked estimates
- Insights with temperature and cycle-length charts
- Cycle history for reviewing and correcting past cycles
- Home-screen widget on iOS showing your cycle day and estimated phase

ESTIMATES YOU CAN INSPECT
Next period, higher-fertility days, and ovulation timing are estimated from your logged history. Calendar estimates may be wrong and do not confirm ovulation. Vellum is for personal awareness, not diagnosis, treatment, or contraception. Consult a qualified clinician before medical or contraceptive decisions. Sources and methodology are available inside the app.

LOCAL REMINDERS
Period, higher-fertility, ovulation, and daily check-in reminders are scheduled on your device. Turn each on or off individually.

APP LOCK
Use Face ID, Touch ID, or your device passcode to lock the app. Sensitive content is covered when the app moves to the background.

EXPORT AND IMPORT
Save a JSON backup or CSV of your logs through the share sheet. JSON backups are validated before restoration. Exported copies remain under your control.

SIX LANGUAGES
English, Spanish, French, Portuguese, German, and Arabic.

No sign-in, no cross-device sync, no HealthKit access, no advertising, and no third-party tracking.