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This turns the document back to front: the last page becomes the first and so on. Pages are copied rather than re-rendered, so it costs nothing in quality.

Almost always to fix a scanner. Document feeders that stack their output face-up produce a PDF that reads from the last page backwards, and the fix is a single pass through this tool. It is also useful for documents in right-to-left binding order that were assembled left to right.

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1. Drop the PDF onto this page.
2. Leave the page range empty to reverse the whole document.
3. To flip only part of it, give a range - those pages are reversed among themselves and everything else stays where it is.
4. Press Reverse.
5. The download starts on its own.

Reversing a range does something more careful than it might sound. The selected pages swap positions among themselves, and every page outside the selection stays exactly where it was. Reversing pages 3 to 6 of a ten-page document leaves pages 1, 2, 7, 8, 9 and 10 untouched. A naive implementation that lifted the range out and put it back would shuffle the surrounding pages, which is a subtle way to lose a document's structure.

If your scan is both reversed and double-sided, this tool is only half the fix. Scanning a double-sided stack on a single-sided feeder produces two files - fronts in order, backs reversed - and what you need is Alternate and mix, which interleaves them and reverses the second automatically.

Bookmarks are re-pointed at the pages' new positions, so a table of contents keeps working after the flip.

Everything happens in your browser, so a 500-page scan is reversed without a byte being uploaded.