The anonymous maker asks for nothing: pick a subject, a domain and a block or a whole path, pick a number of sums, and print. Nothing is saved and nothing leaves your browser — the seed and the choice live in the address, and the sheet is laid out on your own machine.
The generator behind an account (/leerkracht/werkbladen) is the same engine, with two things added: a QR code back to the answers, and — once you have set up a class — a QR of its own per pupil. Without a class it stays exactly as anonymous as the maker above.