Red Letter: Period Tracker

Red Letter is a period tracker and period calendar that keeps your log on your phone. There is no account and nothing to sign in to. Your periods, flow, symptoms and notes are stored only on this phone, and Red Letter never sends them anywhere. It needs the internet only for ads.

★ ONE TAP TO LOG
Tap Period started today on the first day and Period ended today on the last. If you forgot, choose the day. Log earlier periods in a moment, and change or delete any of them later from the calendar.

★ YOUR NEXT PERIOD, AS A RANGE
Red Letter estimates when your next period may start from your own recent cycles, never from an average of other people. It shows a range and its basis: around 13 October, between 12 and 15 October, based on your last 6 cycles. With fewer than two cycles logged, it says there is not enough history yet. If your cycles vary a lot, it says the range is rough. If your period is later than the estimate, it tells you by how many days, and nothing more.

★ A CALENDAR YOU CAN READ AT A GLANCE
Logged period days are filled circles, estimated days are dashed rings, and a day with a symptom or a note has a dot, so nothing depends on colour alone. With a screen reader, each day is one sentence.

★ FLOW, SYMPTOMS AND NOTES
Mark each day's flow: spotting, light, medium or heavy. Tap what you notice: cramps, headache, back pain, bloating, tender breasts, acne, tiredness, mood swings, nausea or cravings. Add a note. Everything saves as you go.

★ HISTORY AND STATISTICS
Every cycle with its length and its period's length, and the average of your last six cycles and periods, with how much they vary.

★ PRIVATE ON THE PHONE TOO
- Your log is never uploaded. Android's backup of the app's data is switched off, so a new phone starts with an empty log unless you restore a backup you saved.
- An optional lock asks for your phone's PIN, pattern, password or fingerprint. While it is on, screenshots are blocked and the app is hidden in recent apps. The lock hides the app; it does not encrypt your log.
- On Android 13 and later, the recent apps screen never shows what is in Red Letter.
- Save a backup file or a CSV whenever you like, wherever you choose. The file is not encrypted, so keep it somewhere private.

★ REMINDERS, IF YOU WANT THEM
Both are off until you turn them on: one a few days before the estimated start, and a daily reminder to log. On the lock screen they say only that your period may start in about 2 days, or that it is time to log today.

★ WHAT LEAVES YOUR PHONE: ONLY THE ADS
Ads are shown by Google's ads software, which receives your phone's advertising ID, an approximate location from its internet address and how ads are seen. Red Letter never gives it anything from your log. An ad is only ever shown as you leave History, never while you log. Watch a short video in Settings to turn ads off for a day.

★ WHAT IT DOES NOT DO
Red Letter estimates one thing: when your next period may start. It does not tell you what your cycle means.

Red Letter is not a medical device and does not diagnose, treat, cure, or prevent any medical condition. Consult a healthcare professional for medical advice, diagnosis, or treatment.

Privacy policy: https://dash-fusion.github.io/privacy/list-period