Open Period Tracker

A period tracker that keeps your data to itself.

Open Period Tracker is free and open source. It works offline, needs no account, shows no ads, and stores everything on your own phone.

Download on the App Store Get it on Google Play View source on GitHub

iOS 13+ and Android 5+. MIT licensed. Listed in the stores as “Open Period & Cycle Tracker”.

Why this one

Four things most period trackers do not promise, stated plainly.

Offline

Tracking, predictions, insights, analytics and backup all run on the device. No server, no sync, no waiting.

No account

No sign-up, no email, no password. The app has nothing to log you into.

Free, no ads

No subscription, no premium tier, no in-app purchase, no advertising SDK.

Open source

Every line is public under the MIT license. Read it, audit it, build it yourself.

What it does

Built for daily logging first, with the analysis layered on top of your own history.

Track

Periods and flow on a calendar. Moods, symptoms and notes for any day. A doctor's checklist covering pain, sleep, skin, digestion, energy and more.

Predict

Next period, fertile window and peak day. An on-device model refines cycle length and period duration from your history. Optional reminders.

Understand

Insights and analytics: best and worst cycle days, mood and symptom frequency, phase correlations, 7-day phase forecast.

Eat and move

Phase-aware diet and nutrition guidance, with regional food picks if you share your location. Yoga and breathwork matched to each phase.

Ask an AI, on your terms

Build an anonymised summary of your logs to paste into ChatGPT, Claude or Gemini. Or point the app at your own Ollama server.

Keep control

JSON backup and restore. A demo-data generator to explore the app before you log anything real.

Screens

Swipe to see more.

Home screen: calendar with period days, fertile window and the current phase. Works offline with no account. Insights: seven-day forecast, cycle progress and fertility status Daily log sheet with flow, moods, symptoms and notes Doctor's checklist with findings and pain, sleep and skin data Analytics: cycle length and period duration trends Diagnosis: cycle health score and on-device health summary Diet and nutrition: phase-aware foods and nutrient gaps from logged symptoms Profile: name, cycle settings and JSON backup

Questions

Short answers. The privacy policy has the long ones.

Does it work offline?

Yes. Every feature runs on the device. No connection is required for tracking, predictions, insights, analytics or backup.

Do I need an account?

No. There is no sign-up, login or email. Open the app and start logging.

What does it cost?

Nothing. The app is free with no subscription, premium tier, in-app purchase or advertising.

Can I export my data?

Yes. Profile → Backup exports a JSON file you can keep anywhere and restore later on any device.

Where is the source code?

On GitHub under the MIT license.

Does it send my data anywhere?

No. The app runs no servers and includes no analytics or advertising SDKs. Your logs stay in a local database on the device. Three optional features touch the network only if you use them: opening YouTube links from the Yoga tab, the operating system's geocoder to pick a food region when you grant location access, and an Ollama server you configure yourself for local AI summaries.

Is it medical advice?

No. Open Period Tracker is a tracking and information tool, not a medical device. Talk to a healthcare professional about anything that concerns you.