Métra
A quiet notebook to know yourself, cycle after cycle.
There is a word that has existed for three thousand years.
Mētra. Ancient Greek. It means uterus — but follow the root and you find meter, measure, mother, matrix. The same Indo-European syllable that gave us metro, the rhythm of a line of verse. The idea that the body has its own meter, its own measure, its own time. We named the app after that word because the name is the promise. —
What Mētra is
A digital notebook for menstrual cycle tracking.
Not a dashboard. Not a coach. Not a community. A notebook — quiet, warm, private — that helps you recognize your own pattern without interpreting it for you, judging it against a norm, or turning it into a product.
It lives on your phone. Only there.
What Mētra is not
Mētra is not a fertility tracker. It has no gamification, streaks, badges, or algorithmic suggestions. It does not ask you to create an account. It does not send motivational notifications. It does not compare you to other people.
It knows nothing about you beyond what you choose to record.
It is a tool. It stays in its lane.
What it does
- Daily log — flow, intensity, customisable symptoms, free-text notes. Three taps. No more.
- Monthly calendar — circle-based view with semantic colour coding for flow, predictions, and recorded symptoms.
- Timeline and table — two views of the same historical archive, toggled in one gesture.
- Statistics — average cycle length, period duration, symptom frequency. Data as data, no editorial commentary.
- Prediction — a window of 3–5 days, calculated from your own history with a weighted moving average. No magic: transparent math, yours alone.
- Encrypted cloud backup — Google Drive, Dropbox, OneDrive. Your data is encrypted on the device, with a passphrase you choose, before it leaves. The provider sees a file it cannot read.
- Export and import CSV — your data is yours, in a format readable by any spreadsheet.
Privacy by architecture
Your data is encrypted on your phone before it ever leaves. The cloud provider sees only an unreadable file.
Mētra’s privacy is not a policy. It is an architectural choice.
- Local-first — all data lives in a local database encrypted with AES-256 (SQLCipher). Never on a Mētra server, because there is no Mētra server.
- Zero-knowledge backup — the encryption key never leaves the device. The cloud backup is an opaque blob.
- No proprietary server — Mētra has no backend, no analytics, no telemetry of any kind.
- Open source — the code is right here. Every privacy claim can be verified by reading the source.
Open source
Mētra is distributed under the GPL-3.0 license.
Anyone can read the code. Anyone can verify that it does what it says. Anyone can fork it, improve it, adapt it — as long as they keep it open.
The openness is not a feature. It is the accountability structure. In a category where trust has been so thoroughly broken, the only credible promise is the one you can audit.
Download
| Platform | Status |
|---|---|
| Android | Download APK → |
| iOS | Available on TestFlight — App Store coming soon |
Support the project
If you find Mētra useful, you can support development:
Need help?
Visit the Help centre for usage instructions.
From Ancient Greek μήτρα — womb, measure, matrix. The same root as mother. The same root as matrix.