Core Cycle

Core Cycle is an encrypted period and cycle tracker. Your entries stay on your device, with no account and no servers. The app does not request Android's internet permission, so it cannot send anything itself; your entries leave your device only if you export or back them up yourself.

Log:

• Log today, Started, and Ended buttons, and mark period days
• Flow (spotting, light, medium, heavy), symptoms plus your own, and 9 moods
• Notes up to 2,000 characters
• Hide or reorder chips in Settings

Calendar:

• Month view of logged days, with estimated period days outlined
• A dot marks symptoms, a mood, or a note; tap a day for its summary
• Select days to edit a period

Insights and estimates:

• Period day and cycle ring on Home, and the next period expected around a date
• Estimates from your last 6 cycles, explained in plain words; estimates are approximate
• Average cycle, cycle range, average period, and a chart of your last 12 cycle lengths
• Top 5 symptoms, find days by symptom or mood, and a history of up to 24 cycles
• Leave any cycle out of estimates, or pause all estimates with one switch

Reminders (all optional, off until you turn them on):

• Before your period, 1 to 7 days ahead
• A daily nudge to log, skipped once you have logged
• The lock screen shows only "Core Cycle, Reminder"

Privacy and security:

• Encrypted with AES-256, with the key held in the Android Keystore
• PIN or pattern lock, plus fingerprint if you turn it on
• Hides screenshots and the recent-apps preview
• Erase all data any time; never reads or writes your device calendar

Backup and export:

• Encrypted backups with their own password, saved to a file you keep
• Import a Core Cycle backup or a CSV from a supported tracker
• Export your log as CSV any time (CSV exports are not encrypted)

Trial: every feature is free for 45 days, then a one-time unlock through Google Play, with no subscription. After the trial your entries stay yours to view, delete, and export; new entries and edits need the unlock.

8 app icons, including a plain Tools icon. Works on tablets. No third-party ads, no tracking, no accounts, and no AI inside.

Core Cycle is a record-keeping and calculation tool; its estimates come only from your own entries. It is not a medical device and does not diagnose, treat, cure, or prevent any medical condition. It is not contraception or birth control and should not be used to avoid or plan a pregnancy. Please consult a healthcare professional about your health. For ages 13 and over.