Ripening, not days
Every jar keeps its own temperature history. Move it to the cellar and the whole schedule shifts with it — while what is already in there stays put.
Your jar counts degrees,
not days.
Every recipe says three weeks. In a cellar at 15 °C it takes six; on a kitchen counter at 24 °C barely two. Fermento works with that difference — to the day, to the gram.
Three jars free, forever. Complete for a one-off € 8.99. No subscription, no account, no adverts.
Same recipe, three kitchens
Twenty degrees does not exist in a real house.
A recipe assumes a kitchen that is not there. This is what the same sauerkraut does in three places where people actually put it.
68 days
In a cold cellar at 12 °C. Slow, and better for it.
21 days
At the 20 °C the recipe quietly assumes.
10 days
On a warm shelf at 28 °C. Fast, and you lose texture.
Two jars, started the same day
This is what a calendar cannot see.
Same cabbage, same salt, same morning. One on the counter, one in the cellar. An app counting down days says the same thing for both.
On the counter24 °C
14 days
In the cellar15 °C
40 days
The line marks the moment the left jar is ready — the right one is then just over a third.
What happens in the jar
Safe is not a feeling. It is a number.
The first question everyone asks. The answer is in the acidity: within three days it drops below 4.6, and that is where it ends for the bacteria you do not want. After that it is purely a matter of taste.
day 0 – 3
Leuconostoc
Gets it going, makes carbon dioxide and the first acids. This is the fizzing.
day 3 – 14
L. plantarum
Takes over and acidifies. This is where it gets its character.
from day 14
L. brevis
Finishes it off. The flavour deepens, the acidity rounds out.
What is in it
Everything a jar needs.
Brine that adds up
Cookbooks run two conventions: percentage of the water, or of water and vegetables together. That is a third of a difference. Fermento shows both.
Twenty recipes
Sauerkraut, kimchi, pickles, hot sauce, kombucha, kefir, sourdough. With ratios, method, and a timeline on your temperature.
Kahm or mould
The distinction that matters most and gets explained least. A white film you skim off; something fuzzy with colour means the jar goes.
Your cultures
Scoby, kefir grains, sourdough and ginger bug. With a feeding rhythm that runs on temperature too: put away cool, nothing needs doing for months.
Jars and planner
What vessels you own, what is free, and what is at its best this season. Kimchi in November, pickles in July, peppers late August.
All on your device
No account, no server, no reading that ends up elsewhere. Exporting to a file takes one button, and so does wiping it.
Works without signal
There is no server, so there is nothing to connect to. In a cellar it just does what it should.
Inside the app
This is what it looks like.
Check it yourself
Where is your jar?
The same formula the app runs. Put in what it is where you are.
21 days
is how long it takes for you. Try 15 or 25.
What it costs
Everything open
Once, or never.
No subscription. This app runs on your own device; there is no server behind it costing money every month.
Free
€ 0 forever
- Three jars at a time
- All twenty recipes
- Every calculator
- Ripening by temperature
- Notes, pH and one photo per jar
- The full knowledge base
- Export and restore
Complete
€ 8.99 one-off
- Unlimited jars
- Cultures, with the scoby hotel
- History and advice from your own batches
- Jar stock and seasonal planner
- Photos without a limit
- Share as a card
- No adverts, ever
Three jars free, forever. Complete for a one-off € 8.99. No subscription, no account, no adverts.
The deal
The app does the maths.
The app does the maths.
You make the call.
That sounds like hedging. It is the opposite: it is exactly why the numbers above are worth anything.
Fermento measures nothing
There is no thermometer in your phone and no pH meter in your jar. Everything the app knows, you typed in. Tell it 20 degrees where it is really 14 and it will calculate the wrong answer beautifully — with no way of noticing.
Every number is a model
A good model, built on the growth curve of lactic acid bacteria and backed by a suite of 128 checks. But a model is still an average of how things usually go, and your cabbage is not an average cabbage.
Whoever smells it, decides
An app claiming your jar is safe would be lying — it is not in the room. That is why every screen in Fermento says the same thing: the timings are a calculation, your nose and your tongue decide. When in doubt, it goes out. A head of cabbage costs two euros.
In plain terms: Fermento is a calculator with a memory, not a food inspector. It is not a food safety assessment, it is not medical advice, and it does not replace your own judgement. What ends up on the table is your call — and that is the only place that call belongs.
Questions
What people ask.
Why doesn't Fermento just count days?
Because a day at 15 °C is not a day at 24 °C. Lactic acid bacteria work faster as it gets warmer, and the difference runs to a factor of four. A calendar counter says the same thing for both, which is exactly why the same sauerkraut turns out perfect one time and limp the next.
Is fermenting at home safe?
Yes, and that is not reassurance but a consequence of how it works. Within a day or two the acidity drops below the point where pathogens give up, and the salt holds them off until it does. What you do have to do: use enough salt, keep everything under the brine, and use your nose. Spoilage in a ferment does not hide.
Does the app tell me my jar is safe?
No, and it could not. Fermento works out how far the ferment has come at the temperature you entered; it cannot see your jar, smell it or measure anything. Every number is a calculation on the data you typed in. Whether something reaches the table is your call — when in doubt, it goes out.
And if something does go wrong?
Fermento is an aid to fermenting, not a food safety assessment and not medical advice. Responsibility for what you make and eat is yours, as with any cookbook. If you feel ill after something you made yourself, see a doctor, not an app.
Do I need an account?
No. No account, no sign-up, no email address. Everything lives on your own device and goes nowhere. You can write your data out to a file and load it back.
What is the difference between kahm and mould?
Kahm is a thin, flat, white film on the brine: harmless, tastes dull, skim it off and carry on. Mould is fuzzy, stands up from the surface and has colour — blue, green, black or pink. Then the whole jar goes, not just the top layer.
Why does my brine percentage never add up?
Because two conventions run side by side. One takes the percentage of the water, the other of water and vegetables together. With one litre of water and 700 grams of vegetables that is 30 grams against 51. Fermento works on the total and always shows the other figure alongside.
What does Fermento cost?
Free for three jars at a time, with every recipe, every calculator and the full knowledge base. Fermento Complete is a one-off € 8.99 and lifts the limit, plus cultures, history, jar stock and the planner. No subscription.
Does the app work offline?
Completely. There is no server, so there is nothing to connect to. That is also why it just works in a cellar with no signal.
When will it be in the stores?
We are working on it. Write to info@nonius.be and you will hear first — nothing else will happen with your address.
A jar you forget is a jar you throw out.
Three jars free. Complete € 8.99 one-off.