Your data stays on this device. Periods are saved to this browser's local storage only — no account, no upload, no analytics on the entries themselves. Export a CSV any time to take it with you, or clear everything in one click.
Start by logging your last period. Pick the start date and approximate duration. After 2+ entries we can start predicting cycle length and your next period.
Log a period
Start date
Duration (days)
Flow (optional)
Notes (optional)
This is a tracker, not a diagnostic tool. Cycle predictions are based on averages of your logged data and textbook luteal-phase length (~14 days before the next period). Real cycles vary widely. If predictions feel off, log more cycles — accuracy improves with data. For pregnancy planning, contraception decisions, or any concerning symptoms, talk to a clinician.
Log periods month-over-month. Cycle history, average length, next-period prediction, current phase. Stays on your device.
Everything happens on your device. Close the tab and it's gone.
Built browser-first. Run by one developer.
Every tool runs on your device. No tracking pixels, no sign-up to start. The numbers below are pulled live from the registry.
386
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7
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34
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27
AI tools
Powered by Claude API
Files never uploadNo tracking pixelsNo sign-up neededWorks in any modern browser
The handful of AI tools (paraphrase, summarise, blog, captions, etc.) send your prompt text to Anthropic's Claude API to do the work. Files, images, PDFs and video never leave your device. Pick the tools that fit your privacy comfort.