What is Rosella Rhythm?

Rosella Rhythm is a free, open-source menstrual-cycle tracker that you run on your own server. Log your period start dates, and it learns your rhythm: a calendar of past and predicted periods, a countdown to the next one, and statistics about your cycle over time.

It is part of the ofbirds.org flock, and it follows the flock’s rules:

  • Always self-hostable. You install it on a machine you control — a home server, a NAS, a small VPS. There is no hosted version to sign up for.

  • Your data stays yours. Cycle data is about as personal as data gets. With Rosella Rhythm, the database lives on your server and never leaves it.

  • Money is optional. The app is free and open source (AGPL). Donate if it helped you; otherwise you only pay for whatever box you run it on.

What it does

  • Track cycles — log period start dates and how long each period lasted.

  • Predict what’s next — the app projects your upcoming periods (15 cycles ahead) from your average cycle interval, and shows a "next period in N days" countdown.

  • Calendar view — a month calendar with color-coded period marks, a marker for today, and a countdown badge on the predicted next period.

  • Statistics — a dedicated stats page with cycle-length charts, a period- duration view, a length-distribution histogram, a year heatmap of period days, and prediction-accuracy tracking.

  • Email reminders (optional) — if you connect an email account, the app can send you an opt-in reminder before a predicted period, and a note when a new app version is released.

  • Works offline — it is a progressive web app (PWA): add it to your phone’s home screen and it keeps working with cached data even without a connection.

  • Comfortable to use — mobile-friendly, light and dark themes, and WCAG AA accessible.

What to expect

The app is intentionally simple: it tracks dates, not symptoms, moods, or temperatures. Predictions are statistical averages of your history — the more cycles you log, the better they get. Accounts are protected by a password; each person’s data is their own.

Ready to try it?

Head to the self-hosting quick start — if you have Docker on a machine somewhere, you are about ten minutes away from a running app.

The source code, issue tracker, and release notes live on GitHub.