Organize PDF shows every page of your PDF in a grid and lets you rebuild the document before saving it. Drag pages to a new position, or select one or more pages and move them earlier or later with the arrow buttons. Rotate the selection left or right, delete it, or insert a blank page after it; blank pages take the size of the page next to them. Every change can be undone, up to 50 steps, and Reset all changes takes you back to the original.
Nothing is written until you press Save organized PDF. The tool then rearranges the original file with pdf-lib in your browser, so the document's title and author, links, form fields and bookmarks to the pages you kept come through unchanged. Each card shows its new position and, if it moved, where it was before, so you can check the result at a glance.
Honest limits: rotation is in quarter turns, which fixes sideways or upside-down pages but not a slightly crooked scan. Deleted pages are removed from the file completely. Password-protected PDFs and PDFs locked against editing need to be unlocked first, and files up to 200 MB are accepted, though a PDF with hundreds of pages is easier to handle on a laptop than on a phone.