MyDays X Join the beta
MyDays X Period & Ovulation Calendar

Go with your flow.

Track and predict your period and ovulation. Your symptoms, your notes and your intimacy life, in one calm place. Easy and uncomplicated.

an app that moves like you do · since 2008

Join the beta iPhone Android

The all-new MyDays X is nearly here.Das neue MyDays X ist fast da.

We are in the last round of testing before the release. Have a look at the preview below. If you would like to try the latest beta first and tell us what you think, you are welcome to join: your feedback is the last piece we are waiting for.Wir sind in der letzten Testrunde vor der Veröffentlichung. Schau dir unten die Vorschau an. Wenn du die neueste Beta zuerst ausprobieren und uns sagen möchtest, was du denkst, bist du willkommen: dein Feedback ist das Letzte, worauf wir warten.

Join the latest betaNeueste Beta testen
In the beta

Widgets that steal the show

Your rhythm, at a glance. On your home screen.

Large widget, Ocean look: the average cycle length of the last 6 cycles as a small line chart, with next period in 6 days and next ovulation in 20 days.
Ocean
Small widget: next period in 6 days.
Small widget: next ovulation in 20 days.
Medium widget, Ocean look: next period in 6 days, next ovulation in 20 days, and the week ahead as a row of dots.
Medium widget, Black look: next period in 6 days, next ovulation in 20 days, and the week ahead as a row of dots.
Black
Small widget, Black look: next ovulation in 20 days.
Medium widget, White look: next period in 6 days, next ovulation in 20 days, and the week ahead as a row of dots.
White
Small widget, White look: next period in 6 days.

Sample data shown. Estimates, not a medical device.

A very short comic

Meet Ms. Harvey

Panel 1: Ms. Harvey, a white cat with a blonde curl and a purple scarf, glares at a goldfish bowl. Inside, the goldfish watches a cat video on a tablet.

One more time a stupid cat video... and I eat the goldfish.

Panel 2: the goldfish and a small pink shrimp watch a cheerful cartoon cat on the tablet. Cat video no. 4,812
Panel 3: a close-up of Ms. Harvey with a furrowed brow and a very unimpressed look. …
Panel 5: Ms. Harvey grins widely with all her teeth. The goldfish is gone and the small shrimp stands alone in the bowl, looking shocked.

Same grumpy guy rebuilt your favorite period and ovulation calendar from the ground up.

The background

18 years, one person.

Most apps like this one belong to a company. This one belongs to me. Here is how it happened, short version.

I really wanted to change something in my life. What came back to me was the advice of a friend and teacher: focus on supporting women.

2008 · Christian Albert Müller
  1. DahabRomania
    2008 · DahabBack and forth between Dahab and Romania, wanting a change. The advice came back: focus on supporting women.
  2. The first smartphonesOnly very simple trackers out there. I thought I could do that better.
  3. 2013 and afterMy daughter was born. The app kept running without me, and copies appeared.
  4. 2026 · nowBack at the keyboard, building with the machine instead of against it.
  5. What comes nextThe new MyDays X reaches more phones, step by step. No dates, no promises.
2008 · Dahab

Between a fishing town and Romania

I had left Bavaria years before. I was travelling back and forth between Dahab, a fishing town on the Red Sea, and Romania, and I really wanted to make a change in my life. That is when I remembered the advice of a friend and teacher: focus on supporting women.

The first smartphones

I thought I could do that better

The first iPhone and Android phones were coming out. I started researching what was already there and found only very simple trackers. I thought I could do that better — with a calendar, with notes, with all of that. MyDays was born.

2013 and after

Then the years rolled

My daughter was born, and that was more exciting than code. I handed the app to freelancers and drifted away from the source while it kept running without me. Other apps copied it, some of them better looking than mine. That is the price of going first, and going first was still worth it.

2026 · now

Back at the keyboard

I came back because the tools finally let me build with the machine instead of against it. MyDays X has been rebuilt from the ground up, not painted over. Same calendar you know, underneath it a new app, on eighteen years of knowing what it is for.

There is no growth team here and no marketing department. When you write, it lands on my desk. That is either the charming part or the slow part, depending on the day.

Read the long version
Simple, on purpose

How you use it

There is not much to learn. Four things, and the rest you will find on your own.

Mark the day it starts

Tap the day your period began. That is the whole setup. Nothing else is needed before the app is useful to you.

Let it do the counting

The calendar shows the days it expects next and your ovulation, and tells you at a glance which day of your cycle you are on today.

Tap a day, add what happened

Symptoms, a note, intimacy, your blood pressure, pulse or blood sugar. A photo, if you want one. Only what you feel like writing down.

PDF

Look back when you need it

Your chart and your statistics, and a report you can export as a PDF and take to your doctor instead of trying to remember.

Lock it

A passcode, or Face ID, so the diary opens for you and not for whoever picks up the phone.

Back it up

Send an encrypted backup to your own email before every update. It stays yours — on your side, not ours. How that works.

In your language

Not only the menus. The symptom names, the daily cards, the reminders. That part took a while.

Write to me

There is a message thread to me inside the app. It comes straight to me, not to a ticket system.

More detail, and the questions people actually ask, are in the introduction and the FAQ. What happens with your data is written out in plain words in the privacy policy.

You decide

You picked this look

In July I spent two days playing art director instead of fixing bugs, and instead of one design, eight completely different ones fell out of it. Same app, same calendar, same hand. Eight personalities.

This app has been shaped by the women who use it for eighteen years, so it did not seem right to pick the front door alone. I put all eight up and asked which one felt like you.

Tap a name to try it on. Ocean won the vote — see the vote.

A tide runs on the moon, about twenty-nine and a half days to the round. A cycle runs close to the same length. I am not going to claim the two are connected. It is simply a rhythm you already know, and that is why the water fits.

Sunlight, deep water, and the pearl you have had in your pocket all along. The calendar inside stays exactly the one you know. Only the front door gets new paint.

The Ocean look: three panels of the MyDays X app store artwork, sunlit water above, deep blue below, and the calendar on a phone held in one hand.
The Ocean look, as it went to the vote on 28 July 2026.
What is coming

The big one is being tested right now

The app has been rebuilt from scratch, with privacy, security and education as the priority, and without losing the touch of entertainment. Health should not be boring.

A group of testers is living in it every day and telling me what is still wrong. I fix it and hand it back to them. That is the whole method, and it is slower than a launch date.

When it is ready for everyone, it will be in your app store. Bringing your years across is the part I have worked hardest on, and I would still send yourself a backup before you update. No date from me here, and no list of promises.

no promises,
just results The same way it has gone since 2008. You will hear about it when it is done, not before.
One desk

Write to me

A question, something broken in the app, or a request about your data. Write, and I read it. If you are in the app already, the message thread in there reaches me the same way.

Write to me email@mydaysx.club
The last page

Comeback Era: a 26-second flip through the comic, with music

Read what the video says

A comic book flips open at speed. Cover: Comeback Era, issue number 1, MyDays X, go with your flow, since 2008. Meet Ms. Harvey, a very short comic: a white cat, a goldfish, one cat video too many, a black panel with speed lines, then a very wide grin. “Trust me, I said so.” Rebuilt, from the ground up. Period, track it. Ovulation, see it coming. Widgets that steal the show. 20 plus looks. Your data stays on your phone. Lock it, with a passcode or Face ID. Back it up, an encrypted backup to your own email. Your language, not only the menus. Write to me, it lands on my desk. 1 million plus downloads on Google Play, 45 thousand plus reviews. 18 years, one person. We don’t bite. Ms. Harvey might. Pages fly by, then it goes calm: MyDays X, go with your flow. With love from Munich, connect with me. Join the beta, iPhone, Android. Music: a short cut of an original song.

Widgets and screens shown with sample data. Estimates, not a medical device.

With love from MunichConnect with me

Join the beta iPhone Android

The store still has the old version.Im Store liegt noch die alte Version.

The all-new MyDays X is not in the App Store yet. We will let you know right here when the rollout begins.Das neue MyDays X ist noch nicht im App Store. Sobald der Rollout beginnt, sagen wir es dir genau hier.

Join the latest betaNeueste Beta testen Open the old version anywayAlte Version trotzdem öffnen