Core, home

← All apps

Core Cycle

Encrypted Period & Cycle Tracker. No Accounts. No Tracking. No Cloud. No AI.

Get it on Google Play

Screenshots

  • Core Cycle home screen: Period, day 4, the cycle ring, today's summary, and the Log today, Started, and Ended buttons
  • Core Cycle calendar for October 2026 with logged and estimated period days and the summary for Oct 30
  • Core Cycle log sheet for Oct 30, 2026 with the Period switch and Flow, Symptoms, and Mood choices
  • Core Cycle Insights screen with average cycle, cycle range, average period, cycles logged, and a chart of the last 12 cycle lengths
  • Core Cycle calendar for October 2026 in a peach color theme
  • Core Cycle Insights screen in a mint color theme

About this app

Core Cycle is an encrypted period and cycle tracker. Your entries stay on your device.

Log

  • Log today, Started, and Ended buttons
  • Mark period days
  • Flow: spotting, light, medium, heavy
  • Symptoms, plus your own
  • 9 moods
  • Notes up to 2,000 characters
  • Hide or reorder chips in Settings
  • Reopens where you left off

Calendar

  • Month view of logged days
  • Estimated period days outlined
  • Dot marks symptoms, a mood, or a note
  • Tap a day for its summary
  • Select days to edit a period
  • Eye button shows or hides grid lines

Insights & estimates

  • Period day and cycle ring on Home
  • Next period expected around a date
  • Date range on most days
  • Estimates from your last 6 cycles
  • Estimates are approximate
  • Typical length on the ring, average in Insights
  • Average cycle, cycle range, average period
  • Cycles logged, and how much they varied
  • Chart of your last 12 cycle lengths
  • Top 5 symptoms from the last 6 cycles
  • Find days by symptom or mood
  • Cycle history of up to 24 cycles
  • Leave any cycle out of estimates
  • One switch pauses all estimates
  • How estimates are calculated, in plain words

Reminders

  • All optional, off until you turn them on
  • Before your period, 1 to 7 days ahead
  • Daily nudge to log, skipped once logged
  • Times are approximate
  • Lock screen shows only Core Cycle, Reminder

Privacy & security

  • Encrypted with AES-256
  • Key held in the Android Keystore
  • PIN or pattern lock
  • Fingerprint if you turn it on
  • Choose how often it asks
  • Hides screenshots and recent-apps preview
  • Erase all data any time
  • No account, no servers
  • Never reads or writes your device calendar

Backup & export

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

Look

  • 8 app icons, including a plain Tools icon
  • Works on tablets

Offline by design
Core Cycle does not request Android's internet permission, so the app cannot send anything itself. Your entries leave your device only if you export or back them up yourself.

No Third‑Party Ads. No Tracking. No Accounts. No AI Inside.

Pricing

  • Free for 45 days, every feature
  • Then a $9.99 one-time unlock
  • No subscription
  • Trial ends after day 45, even mid-period
  • After that, view, delete, and export
  • New entries and edits need the unlock
  • Purchase goes through Google Play

Core Cycle is a record-keeping and calculation tool. What it shows depends on what you enter, and its estimates come only from your own entries. Core Cycle 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.