Why Page Numbers Matter More Than You'd Think
Page numbers are the quiet backbone of any serious document. They let a reviewer say "see page 12", keep a printed stack in order after it's dropped, satisfy thesis and court-filing formatting rules, and make a long contract navigable. Yet documents exported from slide decks, design tools and many web apps arrive with no numbering at all — and adding it by hand, page by page, is exactly the kind of tedium nobody has time for.
Position, Format and How They're Stamped
Choose where the numbers go — bottom centre, bottom left, bottom right or top right — and whether you want a plain sequence (1, 2, 3 …) or the fuller "Page 1 of N" style that tells readers how much is left. The tool then draws the number into the margin of every page with pdf-lib and saves a new file. The numbering is real page content baked into the document, so it survives emailing and printing.
Everything happens in your browser; the document is never sent to a server.
Tips for Long Documents
Pick a corner that won't collide with existing headers or footers, and prefer "Page X of N" for anything that will be printed and physically handled, so a missing page is obvious at a glance. If you've just merged several files into one report, number it last so the sequence runs cleanly end to end.