Merge front and back scans (interleave PDF)

The first file in the list is treated as the fronts and the second as the backs. The result takes one page from each in turn: front 1, back 1, front 2, back 2 and so on. With the reverse option on, the backs file is read from its last page to its first, which is what a flipped stack produces on a scanner without a duplex unit.

Every page is copied as it is — scan quality, page size and orientation don't change and nothing is re-compressed, so the result is about the size of the two files together. If the combined scan is too big to email, run it through Compress PDF afterwards.

Yes. Your files are only used to create your result — they’re never shared and never used to train AI.

When you turn a stack over to scan the other side, the last sheet is now on top, so its back is scanned first. The reverse option reads the backs PDF from its last page to its first to undo that. If your scanner kept the original order, turn the option off.

Pages are alternated while both files still have pages; the remaining pages of the longer file are added at the end. If a page is missing in the middle, add a blank one first with Add Blank Pages so the pairs line up.

Yes. Open the result in Rotate PDF or Organize PDF and turn the affected pages 180°. Interleaving keeps each page exactly as it was scanned.