Questions, answered.
Short answers about the app: what it does, where it runs, and what happens to your diary.
The app
What it is and where it runs.
5 questions
What is Sourdough Diary?
Sourdough Diary is an app for iPhone and iPad that guides you through sourdough baking. It also runs on Apple Watch. It predicts when your starter will peak, plans a bake backwards from when you want bread, runs every stage with a timer, and keeps a diary of every loaf.
Is it free?
Yes. The app is free, with no purchases inside it.
Which devices does it run on?
iPhone and iPad with iOS or iPadOS 17.6 or later, and Apple Watch alongside the iPhone. There is no Android version.
Which languages?
English and German.
Who is Madame Crumb?
A fortune teller in the app. Add a photo of your loaf's crumb and she deals the cards and reads its future. It is a joke, and you can switch her off in Settings.
Starter and bread
What it does on a baking day.
5 questions
How does it know when my starter will peak?
It starts from how long your starter takes after an equal feed, then adjusts for how much you fed it and how warm your kitchen is. When you tell it the jar has peaked, it corrects itself, so the next prediction is closer.
Can I keep more than one starter?
Yes. Each jar has its own name, feedings, reminders and flour, for example a wheat starter and a rye starter side by side.
I have never made a starter. Can I still use it?
Yes. Starter School walks you from flour and water to a living starter one day at a time, and adapts to what your jar is doing.
Does it have recipes?
No. It is a guide, not a recipe collection. You enter your own flour, water and starter, and it times the bake and tells you what to do at each step.
Can I bake without a fridge proof?
Yes. You can proof the shaped loaf overnight in the fridge or on the counter the same day.
Your data
Where your diary lives, and who can see it.
4 questions
Do I need an account?
No. There is no sign-up and no login. You open the app and start.
Where is my diary stored?
On your device, and in your own private iCloud if you use iCloud, so it syncs between your iPhone and iPad. The developer cannot read it. You can also save a backup file.
Does it work without iCloud?
Yes. Without an iCloud account everything stays on the device and the app works fully. It just does not sync to your other devices.
Does it collect data about me?
Not unless you switch it on. Anonymous usage statistics are off by default. The starter family tree shares a few details about one jar with the people you invite, and only if you use it.
Updated 6 October 2026