About the Alternate & Mix PDF
Combine the front and back sides of a double-sided document that was scanned in two passes. Add the PDF of the fronts and the PDF of the backs, and get one file with every page in the right order: 1, 2, 3, 4…
It fixes the most common problem with single-sided scanners and document feeders. Your files are processed on your device.
How it works
Pages are taken one at a time from each file in turn: front 1, back 1, front 2, back 2, and so on. If one file has more pages, the extra pages are added at the end.
When you scan the fronts, turn the stack over and scan the backs, the backs come out last page first. With "reverse order" ticked (the default) the back sides are read from the end, so they still pair with the right fronts.
Pages are copied as they are, keeping their text, images and links.
Assumptions and limits
- The first file is the front sides, the second the back sides; swap them with the arrows if needed.
- Password-protected PDFs need the password removed first.
- The document details (title, author) come from the front-sides file.
Worked examples
A 10-page double-sided contract
Scan the 5 sheets' fronts, turn the stack over and scan the backs. Mixing gives pages 1 to 10 in order.
Backs scanned in the same order
If you rearranged the stack before scanning the backs, untick reverse order so back 1 follows front 1.
An odd number of pages
A 7-page document has 4 fronts and 3 backs; the last front is placed at the end after the pairs.
How to use the Alternate & Mix PDF
- Add both PDFs. Front sides first, back sides second.
- Set the order of the backs. Reversed is the usual case.
- Mix and download. One file in reading order.
Frequently asked questions
Why are my scanned back pages in reverse order?
When you turn the whole stack over to scan the other side, the last sheet's back is scanned first. That's why reverse order is ticked by default, so each back ends up after its own front.
What if the two files have different page counts?
Pages are paired for as long as both files have pages left; the remaining pages of the longer file are added at the end in order. The result shows how many fronts and backs were used.
Can I use it to merge two different documents page by page?
Yes. Any two PDFs can be interleaved, for example an original and a translation, so each page is followed by its counterpart. Untick reverse order if both files run forwards.
Does it change the quality of the pages?
No. Pages are copied exactly, not re-rendered, so text, images and resolution stay identical to the originals and links keep working in the combined file.
Is there a page limit?
There's no fixed limit; it depends on your device's memory. Ordinary scanned documents of a few hundred pages work fine on a phone or laptop because nothing is uploaded.
This tool runs entirely in your browser. What you enter or upload stays on your device and is never sent to our servers.