PDFSafeAlternate & Mix Pages
Interleave two PDFs page by page, right in your browser — built for recombining duplex scans.
File A — front sides
Drop a PDF here, or click to browse
Max 20MB
File B — back sides
Drop a PDF here, or click to browse
Max 20MB
How to recombine a duplex scan from two files
Upload your front-sides file as File A and your back-sides file as File B. If your scanner produced the backs in reverse order (the usual result of flipping a paper stack over on a flatbed scanner), check the reverse-order box.
The tool interleaves the two files page by page — front, back, front, back — into one document in correct reading order, without you needing to manually reorder either file first.
Frequently asked questions
What order do the pages end up in?
Page 1 of File A, then page 1 of File B, then page 2 of File A, then page 2 of File B, and so on — alternating one page from each file at a time.
Why would I need this?
The most common case is a scanner without automatic duplex support: you scan all the front sides in one pass, flip the stack, then scan all the back sides in a second pass. This tool recombines the two resulting files into correct front-back reading order.
What does the "reversed order" checkbox do?
On a flatbed scanner, flipping the whole stack over to scan the backs makes them come out in reverse order — the back of your last page scans first. Checking this box reverses File B before interleaving, so the pages still end up matched correctly.
Do both files need the same number of pages?
Yes — alternating page by page only works when both files have an equal page count.
Related tools
- Merge PDF — Combine multiple PDFs into one document, in any order you choose.
- Organize & Duplicate — Drag to reorder, duplicate, or delete pages while seeing every page.
- Split PDF — Divide a whole PDF into several files — every page, or every N pages.