Tools
The calculators that could not be written as a formula over a few numbers. Each takes something the catalogue's specs cannot express — a list, a pay period, an IP address, two time zones — and each shows the working the same way the catalogue does.
Numbers and lists
Anything whose input is more than one figure — a column pasted from a spreadsheet, a set of grades, a radicand.
Money
Each one carries the date of the data behind it, because a rate or an index without a date is a claim about right now.
Time and place
Clocks, zones and the weeks of the year when the usual difference between two of them is wrong.
Networks
The two prefixes every other subnet calculator gets wrong are the ones this was built for.
Body
Estimates from published formulas, reported as the ranges those formulas actually produce.
Chance
Drawn from the browser’s cryptographic generator without modulo bias, and printed beside the odds of what you got.
Every one of these is also an endpoint
8 of them answer over HTTP and through the MCP server as well as on the page, so a model or a script can call them and get back the answer, the working and the source it came from. The API page has the shapes.