Your cycle,
synced with
the moon.
Athena tells you where you are in your cycle and what's coming — privately, on your phone, forever. No account, no cloud sync — your cycle data never leaves your device.
The period tracker that can't sell your data.
Not “won't.” Can't. Your cycle data lives only on your phone — no account, and nothing for us to hand over.
Your data lives on this phone. No account, and no server holds your cycle data — so there's nothing to subpoena. We couldn't share it if we wanted to.
Predictions that admit uncertainty, patterns learned on-device, science that shows its work.
Free features stay free forever. Export everything, any time. Leave whenever you want — with your data.
Privacy you can check, not just trust.
No account, ever
No email, no password, no sign-up wall. Just open it and go.
Works fully offline
No connection needed. Airplane mode changes nothing.
App lock & decoy PIN
Face ID or a PIN — and a second PIN that opens a decoy.
Panic wipe
Clear everything in a moment when you need to — no trace left.
Discreet mode
A neutral name, icon and notifications — nothing gives it away.
Export & leave anytime
Take your full history with you whenever you like. It's yours.
Read the full privacy policy — it's short, because your cycle data never reaches us.
Where you are, at a glance.
A cycle that reads like the night sky — your day, your phase, what's next.
Honest predictions.
Honest predictions. Ranges when your cycles vary — never fake precision.
Patterns, learned on your phone.
Patterns learned on your device. BBT, symptoms, cycle history — yours alone.
Beautiful on iPad, too.
The instruments are already here.
While the app is being built, its arithmetic is on this site as five free tools. No account, no email, and nothing you type is sent anywhere — the same promise, in a browser.
Period Calculator
Your last period plus your usual cycle length, and the next few months laid out on the moon ring — with the spread you should actually expect.
Cycle Length Calculator
Log a few period start dates and read your own numbers: average, shortest, longest, and how much the whole thing moves.
Luteal Phase Calculator
The days from ovulation to your next period — counted exactly when you know the date, and estimated with the uncertainty shown when you do not.
Printable Period Tracker
Build a paper tracker for any month or a whole year, then print it. Flow key, symptoms, an optional temperature row — and a gentler version for a first tracker.
Printable BBT Chart
Graph paper for a cycle: a temperature grid in °C or °F, a row for the coverline, and space for the notes that make a chart readable later.
See all five tools · Read the sourced answers on periods, privacy and the moon
The short answers.
Kept by the moon.
Kept on your phone.
Athena is not in the App Store or Google Play yet — these badges wake the day it lands. Until then, the free cycle tools do the same arithmetic in your browser, today.