Alternate & Mix Two PDFs
Interleave pages from two files, e.g. fronts and backs from a scan.
How it works
- Upload your two PDFs — the “A” file and the “B” file.
- Preview how the pages will interleave.
- Click to merge.
- Download the result — pages alternate A1, B1, A2, B2, and so on. Everything runs locally in your browser, and pages are copied as-is — nothing gets rasterized or re-compressed, so scanned image quality is untouched.
What's a typical use case?
Duplex scanning on a single-sided scanner: scan all fronts into one file, then all backs into another, and this tool interleaves them into the correct front-back order.
What if the two files have different page counts?
Extra pages from the longer file are added at the end, after the interleaved pages run out from the shorter one.
Which file should I upload first, fronts or backs?
Upload the fronts as the first file and the backs as the second — the tool interleaves them in that order, A1 then B1, A2 then B2, and so on.
Do the two PDFs need the same number of pages?
No — if one has more pages, its extra pages are simply added to the end after the interleaving runs out.
Is this the same as duplex printing?
It solves the opposite problem — reassembling scans made on a single-sided (simplex) scanner back into the correct front-back reading order.
My scanner fed the back sides in reverse order — what do I do?
This tool doesn't reverse pages for you. If your backs came out last page first, fix the order in your scanning app first, or run that file through our reorder tool to flip it, then come back and mix as normal.
Can I mix more than two files, or use a pattern other than one-for-one?
Not with this tool — it's built for exactly two files at a strict one-to-one pace: A1, B1, A2, B2, and so on. For anything more custom, like picking pages from several files in a specific order, use our combine & reorder tool instead.
My back-side scans have extra blank pages — will that mess up the order?
Yes — a stray blank page shifts everything after it by one, so fronts and backs stop lining up. Run the file through our remove blank pages tool first, then mix.
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