Luteum

Luteum is a period tracker that keeps your cycle to itself. Everything you log stays on your phone. There's no account, no server, and nothing to sign up for — because Luteum never receives your data in the first place. No analytics, no advertising, no third-party trackers. HONEST PREDICTIONS Most trackers print one confident date. Luteum tells you how sure it is. On your first cycle it says "likely 12–22 Oct" and means it. After a few cycles the range narrows to your own pattern. If your cycles are irregular, it says so instead of inventing a number. And if you haven't logged in a long while, it pauses predictions rather than announcing you're 183 days late. There's no "set your cycle length" box, either. Your cycle length isn't a setting — it's the average of your own recent cycles, recalculated every time you log. YOUR OWN PATTERNS • Cycle length over time, with the range you actually run • How long your periods last • When your cramps hit, by cycle day • How your mood moves across your cycle Every insight shows how many days it was drawn from, and stays hidden until there's genuinely enough logged to say something true. WORTH A CONVERSATION Luteum quietly notices patterns worth raising with a clinician — long or swinging cycles, long periods, severe cramps, a long gap with no bleeding — and can produce a one-page PDF summary you can hand over. It observes; it never diagnoses. YOURS • App Lock with Face ID, Touch ID or a PIN, and a cover so nothing shows in the app switcher • Four app icons, and light, dark or system appearance • Gentle reminders before your period is due, with discreet lock-screen wording • Export everything as CSV, JSON or PDF, any time • Delete everything, permanently, in two taps Luteum is free, in full. If it's useful you can leave a one-time tip to keep it independent — no ads, no data deals, ever. Nothing about your health is ever behind a paywall. Luteum provides estimates for general wellbeing and education only. It is not a medical device and must not be used as a method of contraception, or to plan or avoid pregnancy. Always speak to a qualified healthcare professional about any health concern.