Cycle Sister
Period & Fertility Tracker
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Free
In-App PurchasesWith Ads
About
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
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What's New in Cycle Sister
1.1
July 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
MoreSubscription plans
Monthly Premium
Monthly Premium
$0.991 Month
