An ODERSA service
Understand money before it is too late
What a budget that holds actually is, why a loan costs more than the amount borrowed, how interest works for you or against you, what an insurance policy really covers, and the ways people try to take your money today. The course school teaches almost nowhere, with calculators where you enter your own real figures.
- Free, no account
- No measurement tool in these pages
- CC BY 4.0
Come in through the right door
Three situations, one course
01
I am getting my first money
Where it goes without being noticed, what leaves on its own every month, and what time builds if you let it work.
Open02
There is a contract in front of me
Six questions in order, the sentences that should make you put the pen down, and the right to change your mind.
Open03
I have to talk to someone about it
A forty-five minute session ready to run, what works, and what loses the room in two minutes.
OpenThe 5 calculators
Budget, cost of a loan, interest, insurance, promised return. Your figures, on your own device.
OpenThe 6 traps
Fake adviser, fake parcel, false promise, blackmail, romance scam, fake refund. The signs, and the exact reflex.
OpenThe glossary, 27 words
Excess, cap, depreciation, all-in rate, disposable income. What each word changes for you, with a worked example.
OpenThe promise, and its proof
Your figures go nowhere
A money tool that is any use asks for intimate things: what you earn, what you owe, what your rent costs. That is why everything here is worked out in your browser, on your own device. No amount is sent anywhere, none is saved, not even locally, and one button clears everything immediately.
You do not have to take our word for it. Open the Network tab of your browser, type figures into a calculator, and watch: nothing goes out. Then cut your connection, and the calculation keeps working.
Why this site exists
It is not a question of intelligence
According to the OECD international survey of adult financial literacy, recorded in 2022-2023 across 39 countries and economies, only 42% of adults answer a question on compound interest correctly, and 15% report having been the victim of at least one financial fraud. Both figures tell the same story: people are left to sign commitments whose mechanics nobody ever explained to them.
This service sells nothing, recommends no product, names no bank and gives no personal advice. It explains the mechanics, it makes them calculable, and it shows its sources. That is all, and that is already what is missing.
In numbers, recounted at every release
What this site holds
231
pages served, counted in the site map
5
calculators that run on your own device
6
traps described, each with its reflex
27
money words explained
10
figures tied to their source
13
freely licensed images, credited to their source
0
articles published
These numbers are counted on the site itself at every build, never typed in by hand. The detail is in the /data/impact.json file, and the data is public.
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Free to reuse
Teachers, drop-in services, social workers, guardians, librarians: the text of this site is under the CC BY 4.0 licence, works offline and prints cleanly. You have nothing to ask us, and there is no account for your users to create. The illustrations each carry their own licence, written under the image and set out on the licence page.