What you type never leaves your device. Every one of these tools is compiled to WebAssembly and runs inside this browser tab. There is no server to send anything to, and none of them makes a network request while it works. You can open your browser's network panel and use any of them: nothing goes out.
It matters less here than for some of this workspace's applications and more than you might think. An expression is rarely secret; a matrix of measurements from an experiment, a list of identifiers being compared as two sets, or a table of readings being interpolated between often is, and none of it goes anywhere.
Each tool remembers your settings, and remembers your input while it is small enough
to be worth keeping, under about eight kilobytes. It is kept in your browser's own
localStorage, on your machine, and is never transmitted. That is worth
knowing before you paste a staff list on a shared computer — clearing your browsing
data removes it, and a private window keeps nothing at all. Your chosen language and
theme are stored the same way.
No account, no sign-up, no cookies of our own, no analytics script, no fingerprinting, no error reporting. The pages carry no third-party JavaScript except the advertising described below.
These pages carry advertising, which is what pays for hosting them. An advertising network sets its own cookies and sees your IP address and the page you are on, in the same way it does on any other site. It does not see what you type into a tool: that text is never part of the page's markup and is never sent anywhere. If you would rather it saw nothing at all, an ad blocker breaks none of the tools.
Opening a file reads it into the tab's memory and no further. Saving a result writes it with your browser's own download mechanism. Neither passes through a server.
Exact work is done in fractions and approximate work in decimals to a number of places you choose and the result states. That matters because these tools show their working: an elimination in floating point produces rows with 0.0000000000000002 where a zero belongs, and every step after it is decided by a tolerance somebody picked. In fractions the zero is a zero.
Some of these tools refuse rather than answering, and that is deliberate. An integral with no elementary antiderivative, a matrix with no inverse, a bisection over an interval with no sign change, a tangent at ninety degrees: each is a fact rather than a failure, and each says which. A plausible number in its place would be worse than the refusal, because you would believe it.
Every result here is the arithmetic done exactly on what you typed. Whether it answers the question you were set, and whether you are allowed to use it, are questions this cannot see. The working is shown so that you can check it, which is the point.
The same tools are also built as a desktop application. It has no network code at all — not for updates, not for anything — and stores its settings in one small file in your user configuration directory.
If this ever changes, this page changes with it, and the change will be visible in the project's history rather than announced quietly.