About this app

Cycle Sister is a private, local-first period and fertility tracker. Log your period cycles, track predictions for next cycle, fertile window, ovulation day, and safe windows. All data is kept 100% secure and stored locally on your device. Key features include: • Period start and length logging • Predictions for next periods and ovulation days • Color-differentiated safe/ovulation/predicted periods • Multi-profile support for recording multiple people (Pro features) • Local backup and restore with strong password encryption Privacy Policy: https://sites.google.com/view/cycle-care-app/privacy Terms of Use: https://sites.google.com/view/cycle-care-app/terms

Latest release

What’s New

Version 1.1 Jul 14, 2026

v1.0.7 — Smarter predictions & faster launch • Fixed: predictions now update immediately when you record a new period start or change settings • Fixed: ovulation and fertile window no longer overlap with period days • Improved: calendar markers load asynchronously for smoother scrolling • Improved: app launches significantly faster — ad and billing SDKs now load in the background • Fixed: calendar icons and colors now display correctly after marking a date

Audience growth

Ratings growth

Steady

7-day gain +0

Ratings / day 0.0

30-day gain +0

US rating-count history

0 ratings

Baseline captured. Growth appears after the crawler observes a changed rating count.

Momentum comes from crawler snapshots for the tracked storefront. “Viral growth signal” means unusually fast recent rating gains; it is an indicator, not download data.

Price tracking