Open Period Tracker
A free, open-source period and cycle tracker for iOS and Android. It works offline, needs no account, shows no ads, and keeps your data on your device.
Store title: Open Period & Cycle Tracker. Built by Brand Builder with Flutter. MIT licensed.
Screenshots
What it does
Track
- Log periods and flow (light, medium, heavy) on a calendar
- Record moods (20 to choose from), symptoms and notes for any day
- Doctor's checklist: pain, discharge, skin, hair, sleep, libido, digestion, breast changes, energy, weight
- Period history and a comparison of the current cycle against your average
Predict
- Next period, fertile window and peak day on the calendar and home screen
- An on-device LSTM model (TensorFlow Lite) refines cycle length and period duration predictions from your own history
- 7-day phase forecast and symptom forecast from past cycles
- Optional reminders before a predicted period
Understand
- Insights: best and worst cycle days, weekly logging score, phase-based tips drawn from your own logs
- Analytics: cycle length trends, mood and symptom frequency, phase correlations
- Diet & Nutrition: phase-aware foods, macro and hydration guides, supplement suggestions, and regional food picks if you grant location access
- Yoga: poses and breathwork matched to each phase, with links to practice videos on YouTube
- AI prompt builder: generate an anonymised summary of your logs to paste into ChatGPT, Claude or Gemini
Keep control
- JSON backup and restore
- Demo data generator (one year of realistic data) to explore the app
- Three-step onboarding, skippable
Privacy, stated plainly
- All data is stored in a local SQLite database on your device. The app runs no servers and collects nothing.
- No account, no cloud sync, no analytics SDK, no advertising SDK.
- The app does not encrypt the database itself. It relies on the operating system's protection of app data at rest.
- Network use is limited to three optional things: opening YouTube links from the Yoga tab, the operating system's geocoder to pick a food region (only if you grant location), and an Ollama server you configure yourself for local AI summaries.
Full policy: https://brandbuilder.com.np/privacy-policy-for-open-period-cycle-tracker/ (also in PRIVACY_POLICY.md).
FAQ
Does it work offline?
Yes. Every feature runs on the device. Nothing requires a connection.
Do I need an account?
No. Open the app and start logging.
What does it cost?
Nothing. There is no subscription, premium tier, or in-app purchase.
Can I export my data?
Yes. Profile → Backup exports a JSON file you can keep anywhere and restore later.
Where is the source code?
Here: https://github.com/onepiece92/openPeriodTracker, under the MIT license.
Is it medical advice?
No. The app is a tracking and information tool. Talk to a healthcare professional about anything that concerns you.
Tech stack
| Layer | Technology |
|---|
| Framework | Flutter 3.x, Dart 3.x |
| State management | provider |
| Local database | sqflite (SQLite) |
| Routing | go_router |
| Prediction | tflite_flutter with a small LSTM model trained by scripts/train_lstm_model.py |
| Typography | Google Fonts (Playfair Display, Outfit) |
Architecture is feature-first: lib/features/<feature>/ holds screens, lib/core/ holds models, providers, database and theme.
Getting started
Prerequisites: Flutter SDK 3.x, Xcode for iOS or Android Studio for Android.
git clone https://github.com/onepiece92/openPeriodTracker.git
cd openPeriodTracker
flutter pub get
flutter run -d ios # iOS simulator
flutter run -d android # Android emulator
flutter run -d chrome # web
To regenerate the prediction model:
pip install tensorflow numpy
python scripts/train_lstm_model.py
Store metadata lives in fastlane/metadata/. The landing page lives in docs/ and is served by GitHub Pages.
Contributing
See CONTRIBUTING.md. Contributions must keep the app offline-first and free of tracking. Security concerns: see SECURITY.md.
License
MIT. See LICENSE.
