Who writes this course?

ODERSA, a non-profit association. It is the association that writes, not one person in particular: the content is written, read back and corrected internally, and the method is published on the Our method page. The association’s identity details appear at the foot of every page.

Why is it free? Where is the catch?

There is no account, no subscription, no advertising and no reserved content. The association sells nothing and takes no commission: that is what allows it to recommend no product. A site like this one costs little, because it is entirely static and has no database.

What happens to the figures I type into a calculator?

Nothing. They stay in the memory of the page, for as long as you keep it open. They are sent nowhere, they are not saved, not even in your browser, and the Clear button deletes them immediately. You do not have to take our word for it: the The proof page explains how to check it in three minutes.

Does this site track me?

No: no tracker, no measurement tool in these pages, no tracking cookie, no request to another domain. The fonts and the images are embedded in the site. Your browser’s Network tab shows it in a second, and that is what the black banner at the top of every page invites you to do.

Is this financial advice?

No, never, and that is a matter of principle. We explain the mechanics and we make them calculable; we know neither your situation, nor your constraints, nor your country. Personal advice means knowing all of that, and in many countries it is regulated by law. This site gives you what you need to decide, not a decision.

Why is no bank, insurer or platform named?

For three reasons. Naming a firm looks like a recommendation, even when it is not one. Offers change faster than a web page, so a named comparison would be wrong within six months. And on the trap pages, naming the brand being impersonated mostly teaches which one to copy. So we describe mechanisms, which stay true everywhere and for a long time.

Does it work in my country?

The course does: you reason about a percentage, a debt or a sales trap the same way everywhere, and the calculators impose no currency. What depends on local law, such as legal deadlines or the authority you report to, is kept apart in verified modules on the Your country page. If your country is not there yet, you lose nothing of the course, and that page says where to look.

Why does the selector show 7 languages?

Because the site is built for the 7 languages of the ODERSA fleet, and the selector only makes clickable those that are genuinely translated and served: 7 to date. A planned language that is not yet translated is never a dead link, its code appears greyed out: that way the selector shows what exists and what does not exist yet, without making a promise. French is the reference language: the others are translated from it.

Does it work without a connection?

Yes. Once a page is open, the site installs itself in your browser cache: the calculators, the course and the trap pages stay available offline, and nothing needs the network in order to calculate. The detail is on Offline and on paper.

Can I use it in a classroom, a workshop, a drop-in service?

Yes, without asking us. A forty-five minute session ready to run is on Talking about money, and what is useful to support organisations is gathered on For organisations. No account is needed for the people you work with, and no data is collected about them.

Can I copy, translate, print, republish?

Yes: the text is under the CC BY 4.0 licence, which allows copying, translation, printing and republication, including modified, on the single condition that you credit ODERSA. The illustrations each carry their own licence, written under the image: reused as it is with its credit, an image asks for nothing more, and some ask, if you modify it, that your version stay under their licence. The details and the exact way to credit us are on Licence and reuse. The corpora are also published as open data.

Where do the figures come from?

Every figure served on this site has its line in a public register, with its source and the date on which we read it: the statistics on The sources, the legal deadlines and the authorities of each country on Your country, the date and the licence of each work reproduced on Credits. A numerical fact without that line is not published. The examples in the calculators and the glossary are arithmetic: they prove themselves, with a calculator.

And if a figure is out of date?

Some figures move from one year to the next: they are presented with their date, with the year of the survey in the sentence, and the date on which we read the source on the The sources page. Content up to date as of August 25, 2026. If you see one that has aged, tell us: report an error.

I have just been caught. What do I do now?

Open the page for the trap concerned in The traps: each one ends with the order of the steps to take next. Three things hold in every case: stop sending money, even if you are promised that everything will be released; keep every written trace; talk to someone today. The authorities to contact depend on your country and are shown on Your country.

How do I report an error, or write to you?

A content error is reported on Report an error. For everything else, two addresses: money@odersa.org for the service team, contact@odersa.org for the administration of the association. The Write to us page explains which one to choose.