Fixing a document without redoing it
A scan that came out of the feeder backwards, a slide deck with a divider page you don’t need, an appendix that should have gone at the front: none of these are worth rebuilding from scratch. Load the file, put the pages where they belong, drop the ones that shouldn’t be there, and save a corrected copy.
How the pages work
Every page shows as a small preview, in the order the new file will have, and keeps its number from the original file, so after a few moves you can always see what came from where. Drag a page to its new place, or use the arrows under it to nudge it one place at a time. The cross deletes a page, “Reverse order” flips the whole document, which is the quick fix for a file scanned back to front, and “Delete pages by number” takes out several at once. Undo steps back one change at a time, and “Reset” returns everything to how the file started.
Nothing is changed in your original
The tool builds a new PDF from the pages left in the list, in the order shown, and that’s what downloads. Your original file isn’t touched. Because the copy is assembled from the page contents rather than edited in place, it doesn’t inherit document-level extras: the title and author, and the bookmark outline some viewers show in a sidebar, don’t come across.
What this tool doesn’t do
It doesn’t turn pages the other way up (rotating is a separate job), and it can’t pull pages in from a second file; combining several documents is what merging is for.