Page numbering looks like the simplest job in this whole set, and it has exactly one trap in it. If your document has a cover, and you number every page from 1, then the cover is page 1 and the first real page is 2 — but the reader looking at the first real page sees “2” printed on something they think of as the beginning. Number from the second page instead and start at 1, and now every number in the document is one less than the page it sits on. Either way something disagrees with something else.
The answer is to skip the cover and start at 2, which sounds like an odd default until you see it: the cover carries no number, page two says 2, page three says 3. The printed number always matches the page. This tool does that arithmetic for you, and states how many pages will be numbered before you commit to anything.
The five formats cover what documents actually use. Just the number for anything short. Number and total — “3 of 12” — for anything that might be printed and separated, which is most contracts. The word Page for reports and submissions. Roman numerals for front matter. Each is previewed as the text it produces rather than described, because “number and total” is a phrase and “3 of 12” is the thing you are actually choosing between.
One honest limitation, stated early rather than discovered late. Numbers already printed into a document are part of the page image, not data, so nothing here can renumber them — you would end up with two numbers on every page. Pagination in a PDF is not a field that recalculates the way it does in a word processor, and any tool claiming otherwise is drawing over the old number rather than replacing it.
Free, no signup, no page limit, and no watermark on the way out.