Every page is generated from geometry rather than assembled from artwork, which means there is no image source to credit, no licence to check and no limit on how many variations exist.
Each one comes as a US Letter PDF, an A4 PDF and the SVG vector file. Nothing is rasterised on the way, so a page stays sharp whether it is printed at A5 or blown up to a poster.
The generators run the same code in your browser. Nothing is uploaded, and there is no image to wait for.