A small set of financial calculators built on one premise: a number you cannot check is a number you cannot use.
Free financial calculators are abundant and mostly opaque. They ask for inputs, return a figure, and give you no way to tell whether the figure follows from a correct implementation of a stated rule or from a guess. When two calculators disagree — which they do, often — there is no way to adjudicate, because neither shows its work.
That opacity is not a technical limitation. It is a choice, and it is usually made because showing the formula invites scrutiny.
FigureDeck publishes the formula, the assumptions, the worked examples, the primary source behind every external figure and its retrieval date, and who is answerable for the page. Where a tool cannot answer a question — because it models a fixed rate and you have an adjustable one, or because it computes principal and interest and your real payment includes escrow — the page says so instead of approximating silently.
It is a free reference tool. There is no account, no charge and no upsell. You enter numbers, it does the arithmetic and shows you how, and nothing you type leaves your browser.
The intention is advertising, disclosed and separated from editorial content. There is none on the site at present; the details, and the reason for the delay, are in the editorial policy.