How this site is made
A site of this size is not typed one page at a time, and pretending otherwise would be the first thing worth distrusting. Here is which parts are written, which are assembled from data, and what has to pass before either goes out.
What a program assembles, and from what
The explanatory text around a tool — its introduction, its questions and answers, the tools it points to — is assembled from that tool's own description: its inputs, its units, the formula it applies, the family it belongs to. It is not a paragraph written once and reused, and it is not a paragraph invented about a tool from its name. Where the family is too broad for one answer to be true of every tool in it, that tool gets its own text instead.
How much of it could end up identical from one page to the next is measured rather than assumed. A script walks all 1,820 tools in all six languages and counts how many share an introduction, a set of questions or a list of related tools; the numbers have to stay under a fixed ceiling for a change to ship. On the health, money and property pages the same measurement is stricter still: the count of tools whose explanation does not match their own subject may fall and may never rise.
The worked examples are computed, not typed
When a tool page shows a worked example — these inputs give this result — the result was obtained by running the calculator, at build time, with those inputs. Nobody typed the answer next to the question. It is the difference between an example that documents the tool and an example that contradicts it after a formula is corrected and the prose is not.
Where each figure comes from
Every tool that rests on a published formula or a published table names it on its own page — the correction, the equation, the guideline, the year. Where two definitions are in use, the tool shows the answer under each rather than choosing for you. The methodology page explains the general rules; the tool page is where the specific claim lives, because that is where it can be checked against the number in front of you.
Data that is true on a date carries that date — a fee schedule, a tax scale, a reference table. Read well after it and the result is a starting point, not a current figure.
Six editions, not one translated five times
Each language has its own text, its own URL and its own number and date formats. Two things are checked automatically before anything ships: that no string sits under the wrong language, and that no illustrative example was written once and left identical in all six — the failure that had the English dictionary illustrating its own rules with French words, correctly, and about a language its readers had not come for.
When something is wrong
Some of what is described above exists because it failed first, and every one of those failures was found by looking rather than by being reported. If you find a figure that is wrong, the corrections page explains how to say so and what happens next — including how a fix reaches the other five languages.