The calculators stay on your device
Every numbered instrument on this site computes locally, in JavaScript, inside your browser. The values you type — salaries, weights, medical measurements, data sets you paste — are never transmitted to our servers, because there is no server-side calculation to transmit them to. Those pages are static files; the arithmetic happens on your machine.
This is a structural property, not a policy promise: you can confirm it by opening your browser's network inspector while using any calculator here and observing that entering numbers produces no outgoing requests.
The AI solver is the exception — read this part
The step-by-step solver cannot work this way, and we would rather say so plainly than bury it. When you submit a problem to the solver, the text you typed is sent to our server, where a computer-algebra engine solves it. That much stays on our own machine: the answer and every worked step are computed there, and no third party is involved in producing them.
Nothing goes further unless you ask it to. The answer arrives with a button marked Explain this, and only if you press it is your problem then also sent to a third-party AI provider — currently OpenRouter and Cloudflare. We use their free tiers, and OpenRouter's free service requires permitting the underlying model providers to train on submitted inputs, and potentially to publish them. We cannot promise confidentiality for anything sent that way. Treat it as public.
Practically: do not paste anything private, identifying, or sensitive into the solver. It is built for maths problems, and that is all it should ever receive. We do not attach your name, account, or any identifier to a submission, because we hold none — but the problem text itself leaves our server, and that is a limitation you should decide about knowingly.
We keep a short-lived cache of solved problems so that repeated questions do not consume the daily quota. It stores the problem and its worked answer, nothing about who asked.
What is stored in your browser
- Worksheet log. Each instrument keeps up to eight of your recent scenarios in your browser's local storage so the log survives a page reload. It stays on your device, is readable only by this site, and is erased when you press Clear on the log or clear your browser data.
- Nothing else. No accounts, no profiles, no fingerprinting, and no cookies are set by this site.
Permalinks are your choice
The Copy link button builds a URL containing the inputs you entered, so you can save or share a specific scenario. That link is generated in your browser and copied to your clipboard — it is not sent anywhere unless you choose to share it. Be mindful that a permalink you share does contain the figures you typed.
Analytics and advertising
There is currently no advertising and no analytics on this site — no ad network, no tracking pixels, no third-party scripts of any kind. If either is introduced later, this page will be updated to name the provider and explain what it collects before it goes live, not after.
External links
Instrument pages cite outside references — standards bodies, health agencies, public documentation. Following those links takes you to sites governed by their own privacy practices, which we do not control.
Hosting logs
Like any website, the server delivering these pages may record standard request information (IP address, user agent, page requested) for security and operational purposes. That is a property of web hosting generally; it is not linked to anything you type into a calculator, and it is not used to build a profile of you.
Children
These are general-purpose reference tools, and we do not knowingly collect personal information from anyone, of any age — we ask for no accounts, names, or contact details. Students are an obvious audience for a maths solver, so it is worth repeating the point above in that context: pressing Explain this sends whatever was typed to third-party AI providers who may retain it. A maths problem is fine; a name, school, or anything personal should not go in that box.
Questions
If anything here is unclear or you believe the site behaves differently from this description, please get in touch. A privacy policy that does not match the software is a bug, and we will treat it as one.