Show Bubbie your jar. One photo and she reads it — bubbles, rise, the crust on the glass — then moves your next feed to match. Your crumb too.
Your sourdough starter is alive. Fermento treats it that way.
Klaus — or whatever you name yours — has a face. Leave him too long and he looks hungry. Feed him and he beams. It sounds silly right up until you realise you haven't killed a starter in months.
A PHOTO INSTEAD OF A GUESS
With Plus, hold the jar up to the camera. Bubbie reads the bubbles, how far it climbed, the crust drying on the glass — six things a camera can genuinely judge, not ten invented ones. Then she says what it means for your next feed, and moves it. Photograph a cut loaf and she reads the crumb the same way.
SIX JARS, ONE SHELF
Sourdough starter, brine pickles, kombucha, kraut and kimchi, yogurt and kefir, ginger bug. Each gets its own character, rhythm and checklist.
FROM FLOUR AND WATER
Three day-by-day recipes raise a starter from scratch: the grams for each day, and what you should be seeing. Around day four it looks dead in every one of them — Fermento tells you that before you throw it out.
REMINDERS THAT READ THE ROOM
Free jars run on a fixed rhythm you choose. With Plus, tell Fermento how warm your kitchen is and it pulls the next feed forward on hot days, pushes it back when it's cold. Quiet hours are respected — nothing pings you at 3 a.m. Burp reminders for pickles, fizz checks for kombucha, a wake-up when a jar leaves the fridge.
FEED BY THE SCALE
Tell Fermento once what the empty jar weighs and every feed names the number to watch for instead of an amount to guess at. Your jar can hold a blend — 70 % wheat, 30 % wholegrain rye — and Bubbie says whether that ratio carries it to the next feed.
WHEN SOMETHING LOOKS WRONG
Grey liquid on top? White film? No rise? Photograph it, or pick what you see from a list. Bubbie explains what it actually is, and with Plus installs a real fix: a changed ratio, a shorter schedule, a set number of feeds. The jar stays in rescue mode until it's back on track.
IT LEARNS YOUR STARTER
Log a rise and Fermento remembers how long it took. The countdown to the peak is free and runs on your Lock Screen. With Plus it drops the rule of thumb and uses your jar's own measured curve instead.
PLAN A BAKE BACKWARDS
Say when the dough goes together and Fermento names the feed time and the ratio so the starter peaks exactly then. One plan a month is free.
WHEN YOUR HANDS ARE FULL
"Hey Siri, feed my starter in Fermento." A widget and a Control Centre button do the same in one tap. On bake day the step you're in counts down on the Lock Screen.
EVERYTHING YOU DID, KEPT
A calendar that fills itself and, with Plus, a photo timeline per jar and a monthly recap to share. Dough and brine calculators. Discard recipes so nothing goes in the bin. Your whole log exports as CSV — free, because it is your data.
BADGES YOU EARN
Twenty milestones and twenty-one outfits for your jars. None of them can be bought — they only come from actually looking after your ferments.
WHAT LEAVES YOUR IPHONE
No account, no sign-up, no ads, nothing sold on. Your jars, photos and history live on the device and sync through your own iCloud if you want them to. A photo sent for a reading is resized, stripped of its location, and stored nowhere — not on the server, not in a log. The weather heads-up is optional and sends a rounded-off region, never an address. Anonymous counts show where people get stuck; a switch in Settings turns them off.
FERMENTO PLUS
Unlimited jars, full history, the photo readings, the bake planner, rescue plans, temperature-aware reminders, photo timelines and the bake book. Free keeps two jars and 30 days of history.
Fermento is a logbook, not a lab. It won't tell you whether something is safe to eat - when in doubt, throw it out.
Apple Standard EULA: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/
Terms of Use: https://jonaspolenz368.github.io/Fermento/terms.html
Privacy Policy: https://jonaspolenz368.github.io/Fermento/privacy.html
Ratings & Reviews
5.0
out of 5
2 Ratings
Log a feed when you get round to it.
You feed at seven and reach for your phone at noon. The feed sheet and the peak sheet both carry a time row now, so the entry keeps the hour it really happened — and that is the hour your next reminder, the peak alert and the countdown are all measured from. It defaults to now, so nothing changes if you log as you go.
A late feed mends the day it belonged to. Fed yesterday and only told Fermento today? Then yesterday gets its tick. Your streak closes the gap you were trying to fill, instead of leaving it open and crediting today twice.
And your jar's own curve learns the right numbers. A peak typed in five hours late used to teach Bubbie that your jar takes five hours longer than it does — it now hangs off the feed it really belongs to.
Your own ratio, typed in. Not every jar runs on 1:1:1 — a sweet stiff starter at 1:1:0.5, your main jar at 1:2:1.5. Type it once in the feed sheet and it stays with that jar, with the scale steps and the peak forecast following it. And Bubbie no longer marks a stiff starter down for being stiff.
Write your own discard recipes. Twenty of ours now, nine of them needing no oven at all, because discard piles up on a weekday evening. The one you actually make sits beside them, in your own words and with its own timer.
And share what Bubbie saw in your crumb. The six scores and the crumb shot as one card, straight from the loaf.
Version 2.0.4
Subscriptions
Fermento Yearly
Unlock everything in Fermento for a year.
Free Trial
FermentoPlusMonthly
Monthly access to Fermento Plus
Free Trial
The developer, Jonas Polenz, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Linked to You
The following data may be collected but it is not linked to your identity:
Purchases
Location
User Content
Usage Data
Privacy practices may vary, for example, based on the features you use or your age. Learn More
The developer indicated that this app supports the following accessibility features. Learn More
Supported Features
VoiceOver
Larger Text
Sufficient Contrast
Reduced Motion
Information
Seller
Jonas Polenz
Size
17.9 MB
Category
Food & Drink
Compatibility
Requires iOS 17.0 or later.
iPhone Requires iOS 17.0 or later.
Mac Requires macOS 14.0 or later and a Mac with Apple M1 chip or later.