Change the text that is already on the page in the document's own font, add your own, white things out, highlight, draw, sign with your mouse, stamp checkmarks, drop in images, rotate and delete pages — then download the finished file. Your document is never uploaded anywhere: the whole editor runs on your computer, inside the page. It is free.

Not a text box on top — the actual words on the page, in the document's own font, so nobody can tell it was changed.
Cover anything, cleanly, and the thing underneath is gone from the file you download.
Draw your signature with a mouse or a finger, save it, and drop it on anything from then on.
The marks you actually make on a document you are reviewing.
Point at the thing you mean. Drop in a logo, a photograph, a stamp.
The scanned page that came in sideways, and the blank one at the end.
Point your phone at a piece of paper on a desk and it becomes a PDF you can edit.
The whole editor is in the page. Your document never leaves your computer, because there is nowhere for it to go.
Change a line item and the subtotal, the tax and the total follow. Change the bottom-line total and the numbers above it scale to match, to the cent. The editor finds the relationships in your document on its own — you do not tell it what adds up to what, you just edit.
This is the thing accountants and estimators stop and stare at. A quote where the client wants the total to land on a round number. A statement where one figure was wrong three pages ago. A budget you need to reshape in front of somebody. Work that used to mean rebuilding the document now takes one edit.
Paper photographed into a document, numbers that keep themselves right, and one click out to signature, to a secured link, or into your books — without the file ever touching your downloads folder.
The editor is free because it is the easiest way to show what the rest of this is like.