Credits and licences

Last updated 2026-10-11

Our own code

The tools and page layouts are written for this site. The pages make no requests to other servers.

Formulas and rates

The calculators use standard accounting and finance formulas (margin, markup, break-even, NPV, IRR, payback), typed into our own code and tested against hand-worked examples. Tax and interest rates are entered by you; the few example rates in presets name their official source (GOV.UK, the German Federal Ministry of Finance, service-public.fr) and the date they were checked.

Third-party material

None. No third-party libraries, fonts or data sets are used.