About Danfio

Danfio is a small, independent tool site. It exists for one reason: most online calculators ask you to accept a data policy before showing a number, then bury the method that produced it. We do the opposite — the maths is on the page, the tool runs on your device, and there is nothing to sign up for.

How the tools are built

The site is a static site. Every calculator is a small program that ships with the page and runs locally in your browser; there is no server that receives your numbers, which is why a mortgage or salary figure never leaves your device. A single shared engine powers every loan, debt and payoff calculation, so two tools can never quietly disagree about the same formula.

How the numbers are checked

• Formulas are implemented once, in one engine, and covered by automated tests.
• The worked example on each page is generated by the calculator itself at build time, so the printed answer and the interactive answer are always the same computation.
• Defaults reflect mainstream published averages, and the source of each assumption is listed on the page.

How the site is funded

Display advertising pays the hosting bill. That is the whole business model: we do not sell data, we do not require an account, and we do not hide a calculation behind an email form. If a page ever earns an affiliate commission, it is disclosed on that page.

Not professional advice

These tools produce estimates for planning. They are not financial, tax, legal, medical or insurance advice. Before acting on a number, check it against your own documents and, where the stakes are high, talk to a qualified professional. See the disclaimer and themethodology page.

Questions, corrections or a tool you would like to see? Write toDanfioTools@gmail.com or use the contact page.