Periods and predictions
Flow, spotting and a one-tap "period started". The next period comes with a realistic date range and an honest note on how sure Ebb is.
In development
Free & open source
iOS & Android
Your cycle,
on your terms.
Ebb is a cycle and wellbeing diary that keeps everything on your phone. Track periods, symptoms and moods, see predictions that learn from your own history, and never pay for your own data.
Beta testing is underway. Public App Store and Google Play releases are on the way.
Period & flowSpottingCrampsMoodEnergySleepPain 0–10HeadacheBloatingTender breastsBasal temperatureDischargeOvulation testsPregnancy testsLibido
Period & flowSpottingCrampsMoodEnergySleepPain 0–10HeadacheBloatingTender breastsBasal temperatureDischargeOvulation testsPregnancy testsLibido
Pill remindersMedicationSupplementsMealsWaterExerciseWeightAcneCustom tagsCravingsAnxietyHot flashesBrain fogNotesDaily impact
Pill remindersMedicationSupplementsMealsWaterExerciseWeightAcneCustom tagsCravingsAnxietyHot flashesBrain fogNotesDaily impact
Free, actually free
Your own data shouldn't cost a subscription.
The popular cycle apps keep their best insights behind a yearly plan. Ebb gives you all of it, with nothing held back and nothing to upgrade to.
Flo Premiumabout, per year
Clue Plusabout, per year
Natural Cyclesabout, per year
Ebb$0forever, every feature
Approximate US list prices for yearly plans as reported in 2026 reviews. Prices vary by country and change often; each of these apps also has its own strengths.
Everything in one diary
The features people pay for, without the paywall.
Daily check-ins
Over 30 symptoms, moods, energy, pain and its impact on your day, sleep, sex and libido, pill, medication and your own custom tags.
Patterns, not noise
Average cycle and period length, regularity, symptoms that return before your period, and a look back at how close past estimates were.
Fertility awareness
Basal temperature with shift detection, ovulation tests and cervical mucus. Modes for trying to conceive, avoiding pregnancy or hormonal birth control.
Food and movement
Gentle meal and activity ideas for each phase, and a meal diary. On Android, an optional on-device model can suggest what is on your plate.
Discreet reminders
Period, fertile window, pill and temperature reminders, worded so nothing private appears on your lock screen.
Share with a partner New
Send a link with your predicted period and premenstrual days. Your partner's Ebb gives them a heads-up and ideas for how to help. Only dates, and still no server.
How it works
Predictions that learn from you, and say when they're unsure.
- Your history, not an average woman's.The next period comes from the median of your last six cycles. Unusual cycles, and any you exclude after illness or travel, are ignored.
- Ovulation, counted backwards.Ebb subtracts your luteal phase from the predicted cycle. Temperature shifts refine it and teach Ebb your own luteal length.
- Honest about uncertainty.Irregular cycles get a wider range and a clear note. Predictions are estimates, never contraception.
CYCLE DAY
1
Period
Period
Follicular
Fertile
Ovulation
Luteal
Premenstrual
Private by design
Your diary never leaves your phone.
Cycle data is some of the most personal information there is. Ebb was built so there is nothing to leak, sell or hand over: no server holds your diary.
accounts
servers
trackers or ads
- Optional PIN and Face ID or fingerprint lock.
- Apple Health and Health Connect access is optional and read-only.
- Export a backup or spreadsheet whenever you like, and delete everything in one tap.
- Open source, so anyone can check these claims. Read the privacy policy.
A closer look
Warm, calm and easy to read.
No pink, no flowers, no clutter. Real screens from the current build, shown with sample data.
Switching is easy
Bring your history with you.
Years of logs are too valuable to leave behind. Ebb reads them in, shows you what it found, and keeps anything you already logged by hand.
From Flo
Periods, symptoms, moods, discharge, tests, temperature, notes and more. Anything unfamiliar is kept as a custom symptom.
- Ask Flo for your data in JSON format (Help → Contact us).
- Unzip the file Flo emails you.
- In Ebb, choose "I already use Flo" and pick the file.
From Apple Health
On iPhone, Ebb can read what Flo, Clue or Apple's Cycle Tracking saved to Health: periods, spotting, tests, symptoms and basal temperature.
- Let your old app share with Apple Health.
- In Ebb, choose "Read from Apple Health".
- Review the preview, then add it to your diary.
Open source, MIT licensed
Built in the open, free to reuse.
Read the code, build it yourself, translate it, or fork it for your own community. Ebb is written in TypeScript with Expo and React Native, so one codebase runs on iPhone and Android.
# Try the app in your browser
$ git clone https://github.com/TjebbeHB/ebb.git
$ cd ebb
$ npm ci
$ npm run web
# Or on a phone or simulator
$ npm run android
$ npm run ios
Where things stand
Honest status, version 1.4.
Ebb is in active development and being tested on real phones. Here is what works today.
| Capability | Android | iOS |
|---|---|---|
| Cycle diary, check-ins and insights | Ready | Ready |
| Import from Flo files and Ebb backups | Ready | Ready |
| Health integration | Health Connect: sleep, resting heart rate | Apple Health: cycle records, sleep, resting heart rate |
| Manual meal diary with photos | Ready | Ready |
| On-device meal photo recognition | Built, device testing | Not yet |
| Store release | Test builds | TestFlight being prepared |
Questions
Good to know
Is it really free? What's the catch?
There is no catch. No subscription, no ads, no selling data, and there is no server to pay for because your diary lives on your phone. Ebb is a free project released under the MIT license.
Can I use Ebb as contraception?
No. Predictions are estimates based on your logged dates and averages. Ebb is not a medical device and does not diagnose, treat or prevent any condition. Talk to a healthcare professional about contraception.
What happens to my data if I lose my phone?
Because nothing is stored online, your diary is only as safe as your phone. Export a backup file from Settings → Data now and then, and keep it somewhere you trust. You can import it on a new phone.
How do I get the app?
Ebb is being tested before its store release. You can already run it from the source code on GitHub, and store links will appear on this page once the beta is open.
Does it work for irregular cycles, PCOS or perimenopause?
Ebb predicts from your own history and widens its range when cycles vary, telling you plainly when a date is a rough guide. You can exclude unusual cycles. Dedicated perimenopause and pregnancy modes are not included yet.
Can I help?
Yes, please. Report bugs or ideas in GitHub issues, using made-up example data rather than your own health records. Translations, design feedback and code are all welcome.
A calmer cycle app, for everyone.
Free for anyone who needs it, and open for anyone who wants to make it better.