Your cycle, your data, your way
Free cycle tracking with AI insights, partner sharing, and gamification — built for everyone, not just women.
Everything you need
Powerful features designed around your goals
Goal-Dependent UI
Whether you're tracking for contraception, pregnancy, or general health — the entire app adapts to your goal.
AI Smart Logging
Describe your day in natural language and let AI fill in the details. No more tapping through endless menus.
Partner Sharing
Share a filtered view of your cycle with your partner. They see what you choose to show — nothing more.
Gamification
Daily quests, XP, streaks, and a pixel avatar you can customize. Healthy habits, made fun.
Privacy First
AES-256 encryption, GDPR compliant, full data export. Your data belongs to you — always.
Health Sync
Sync with Apple Health and Health Connect. Steps, sleep, heart rate — all in one place.
How it works
Sign Up
Create your account and tell us your goal
Log Daily
Track symptoms, mood, temperature — or let AI do it
Get Insights
AI-powered predictions that learn your unique patterns
Frequently Asked Questions
Is Cythr really free?
Yes! Cythr is free forever. We use a donations model — if you find the app valuable, you can support development with a one-time or recurring donation. No features are locked behind a paywall.
How does cycle tracking work?
Log your daily data (temperature, symptoms, mood, etc.) and Cythr's AI-powered prediction engine learns your unique patterns. The more you log, the more accurate your predictions become.
Can my partner see my data?
Only if you choose to share. Partner sharing gives your partner a filtered view of your cycle — they see predictions and phases, but you control exactly what's visible. Works for any kind of partnership.
Is my data private?
Absolutely. Sensitive data is encrypted with AES-256-GCM, we're fully GDPR compliant, and you can export or delete your data at any time.
What platforms are supported?
Cythr is available on iOS (via TestFlight) and Android (via Google Play beta). Both apps are native for the best performance and health data integration.
Do I need to log every day?
No, but consistency helps predictions. Cythr has a gamification system with quests, streaks, and XP to help you build healthy logging habits — think of it as a gentle nudge, not a requirement.
Support Cythr
All features are free. Support us to get enhanced AI.
Supporter Perks
- 💬 50 AI messages per day (vs 10)
- 🧠 Richer AI memory — knows your patterns
- ⭐ Priority AI quality for complex questions
- 📊 Daily personalized health insights
Get Early Access
Join the beta and help shape the future of Cythr
iOS
- Install TestFlight from the App Store
- Open the invite link below
- Accept & Install from TestFlight
Android
- Join our Google Group
- Accept the testing program invite
- Install from Google Play