Cycle & period tracker · AI friend

A period tracker that feels like texting your big sister

Open HeySis and Mia asks: “Hey! How are you today?” She remembers your cycle, your mood and how you feel — and explains what’s going on in plain words. No hormone lectures, no pressure.

Download on the App Store See how it works iOS 26+ · free to download, premium is optional
HeySis Today screen with cycle phase and gentle prediction
Mia, the HeySis AI companion

Most trackers give you charts. HeySis gives you someone to talk to.

Meet Mia — your AI companion who knows where you are in your cycle and answers around your own data. “Why is my period late?”, “Is this PMS?”, “Why do I get cramps?” — ask in everyday words.

Ask Mia

Answers around your cycle — not generic articles

  • Mia knows your cycle day and what may be behind how you feel.
  • “This is normal” — Mia’s frequent, honest answer.
  • When a symptom deserves a doctor, Mia says so directly — without scaring you.
  • Mia is an AI friend, not a doctor — and she never pretends to be one.
Chat with Mia about period cramps
Cycle & predictions

A calendar that explains the “off” days

  • Predictions for your next period, ovulation and the fertile window.
  • Cycle phases on the calendar — menstrual, follicular, ovulation, luteal.
  • Late days explained calmly — no red alerts.
  • A month and the whole year on one screen.
Calendar with cycle phases and a day summary
Short, human reads

Understand your body without the overwhelm

Short reads on cycle phases, PMS, period pain and ovulation. The facts come from the NHS and peer-reviewed research; the tone, from a friend.

  • 5-minute reads, zero jargon.
  • Mia offers the article that fits the moment: cramps — about cramps.
Insights: short illustrated articles about the cycle

Log in one tap — only what matters to you

Logging is answering Mia’s question, not filling a form. 100+ options — and none of them required. No streaks, no guilt, no pressure to log every day.

🩸 Period & flow 🙂 Mood & energy 🤕 Cramps, headache, fatigue… 💧 Discharge 🧪 Ovulation & pregnancy tests ❤️ Sex & libido 🧘 Activity 😮‍💨 Stress ✈️ Travel

Private by design

Cycle data is personal. We built HeySis so it stays yours.

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On your device

Your diary lives in a private local database. Optional sync is end-to-end encrypted — even we can’t read it.

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AI only with consent

Before any online AI is used, HeySis shows what would be shared and asks first. You can keep Mia fully on-device.

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Never sold, no ads

We don’t sell your data or use it for ads. The app has no ad SDKs, no third-party analytics, no social logins.

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Health stays yours

Apple Health is optional, read-only background context for Mia. HeySis never writes to Health.

How HeySis is different

Not a dashboard — a conversation.One gentle step at a time.
Not “track everything”.Just what helps Mia understand you.
Not science overload.A friend who keeps it simple and warm.
No streaks, no guilt.No pressure to log every day.

Questions, answered

Is Mia a doctor?

No. Mia is an AI companion for educational support. She doesn’t diagnose, and when something looks like it deserves attention, she suggests seeing a doctor. HeySis predictions are approximate and must not be used as contraception.

Does HeySis work offline?

Yes. The diary, calendar and predictions are fully local. Only the optional online AI, cloud sync and the sharing circle use the network.

Who can see my data?

You. Your diary is stored on your device; optional features only send data after you explicitly turn them on, and you can revoke them anytime. Details in our Privacy Policy.

How do I delete my data?

In the app: Profile → data settings, or simply delete the app. If cloud sync was on, deleting your data in the app deletes the synced copy too.