Built so your personal life stays strictly yours.
A period diary is one of the most personal things on your device. Any app can promise to protect your privacy — Cycle0 is built so there is nothing to protect in the first place. No accounts, no servers, and no tracking.
Running entirely on your device changes what the app can and cannot do. Here is a clear look at that trade-off before you download.
What is held about you
Nothing. Here is the complete list of what is collected:
What this means for you
Total privacy is worth it, but it comes with a few practical trade-offs:
Your entries, under your control
Everything you log sits in Cycle0’s private storage on your device. Three doors lead out, and you hold every key.
Your own cloud
Point backups at your own iCloud Drive, Google Drive, or a local file. Off until you turn it on, and it only saves where you tell it to.
Whenever you need it
Save your history as a PDF for a doctor, or a CSV for your own records. Moving to a new device uses the backup file instead.
Everyday peace of mind
Lock Cycle0 with a PIN, Face ID, or fingerprint, so nobody else can open it if they pick up your device.
A simple diary, not a substitute doctor
Cycle0 is built for honest tracking, not guesswork. It does not diagnose, screen for conditions, or offer medical advice. It runs clean arithmetic on the dates you log and presents forecasts as expected or likely — never as certainty.
For reliable health information, Cycle0 links directly to official sources like the NHS, WHO, and NICHD rather than rewriting them. The design stays calm by design — no clinical symbols, no alarming colors.
Around $4.99 once. Yours forever.
One purchase unlocks everything from day one: advanced logging tools, PDF reports, every theme, all fourteen languages, and tablet layouts. Every future update is included. Prices vary slightly by country, and your store shows the exact amount before purchase.
Why there is no free trial
A free trial needs to know who you are so it can expire. That requires account monitoring and user tracking — the exact things this app exists to eliminate.
Instead, Cycle0 costs around $4.99 upfront on your store. You can see everything beforehand: every screenshot on this site is taken directly from the real app. If Cycle0 ends up not being the right fit, standard store refund policies have you covered.
See every screen before you buy →The plain-English legal summary
Who controls your data?
You do. Nothing is stored remotely, so there is no account to delete and no personal data for anyone else to access.
The App Stores
Apple and Google handle payments under their own terms. Your card details are never seen here.
Not a medical device
Cycle0 is a personal diary, not a diagnostic tool or contraception method. Every entry is self-reported, and printed reports state this clearly for your doctor.