Scanned documents come out of order more often than not — the last page scanned first, a duplicate slipped in, a blank page from the feeder. Fixing that by hand usually means opening a heavy PDF editor for what should be a thirty-second job: drag a few pages around, delete a couple, done.
To reorder, go to the Reorder PDF Pages page and upload your file. Every page appears as a thumbnail — drag them into the order you want, then download. There’s no need to know page numbers in advance; you’re arranging what you can actually see. To delete instead, go to the Delete PDF Pages page, upload your file, and click the ones you want gone — the faster tool when all you need is removal, a blank page, a cover sheet you don’t want included, a duplicate. Both tools work from the same thumbnail view, so if a document needs pages both reordered and removed, you can delete the ones you don’t want on the Reorder page while you’re already rearranging the rest, with no need to run two separate passes on the same file.
This fixes a handful of situations that come up constantly: a scanner fed pages in the wrong order, a document has a few blank pages mixed in from double-sided scanning, you only need certain pages from a larger file in a different sequence than they currently appear, or a cover page or table of contents needs to move to the front. If the PDF is password-protected, remove the password first with Unlock PDF (you need to know it) — an encrypted file can’t be edited by any tool until it’s unlocked.
If the same document also needs a blank page inserted, a page duplicated, page numbers added, or a watermark stamped on, do it all in one sitting with Edit PDF instead of running the file through several tools — see How to Edit a PDF Without Adobe Acrobat for the full walkthrough. It’s the same thumbnail view with every page feature in one toolbar, and everything is applied to a single download; see how to add blank pages to a PDF for the insert-anywhere case specifically. Just need one specific page pulled out as its own file, rather than the rest reorganized? How to Pull One Page Out of a PDF is the more direct tool for that.
Once your pages are organized: rotate any that came out sideways, compress the file, split it into separate files if different sections need to go to different people, or add page numbers if the new order needs to read as one numbered document.
Specific versions of this problem, each with their own writeup: How to Fix a PDF That Scanned in the Wrong Order for when a feeder or a batch scan reversed the sequence, How to Remove Blank and Unwanted Pages From a Scanned PDF for the duplex-scanning artifact, and How to Remove a Sensitive Page Before Sharing a PDF for when the reason for deleting is privacy rather than tidiness.
Reorder PDF Pages or Delete PDF Pages — both free, no login, no watermark, file removed from our servers immediately after.