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.
Moon phases are how Athena draws your cycle — a picture, not a claim that the sky moves it. What the research found.
The tools are already open.
The app's arithmetic also stands in the tools on this site: 13 of them, open to anyone. No account, no email, nothing to pay — the same arithmetic, in a browser.
Period Calculator
Your last period plus your usual cycle length, six cycles laid out on the moon ring, and the whole thing as a printed calendar or a calendar file — windows, never single days.
Cycle Length Calculator
Log a few period start dates and read your own numbers: average, shortest, longest, and how much the whole thing moves.
Period Late Calculator
How late is late, measured against your cycle rather than a textbook one — plus the ordinary explanations, and the day a test would actually mean something.
Ovulation Calculator
The days ovulation is most likely, worked backwards from your next period — printed as a window, because a single day would be invented.
Pregnancy Test Calculator
Three ways in — ovulation, conception, or your last period — and two dates out: the earliest a test is worth taking, and the day its answer can be trusted.
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.
See all 13 tools · Does the moon really drive your cycle? · Read the sourced answers on periods and privacy
The short answers.
Kept by the moon.
Kept on your phone.
Prefer your browser? The free cycle tools are here too — no account, no email.
Other lights, same sky.
Athena is one of a handful of apps from the same small team in Rīga. Different corners of a life, built the same plain way.