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Alternate & Mix PDF

Combine PDFs by alternating their pages — perfect for double-sided scans.

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Add two PDFs, e.g. front sides and back sides. Free tier: up to 50MB total.

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How to Alternate and Mix Pages from Two PDFs

Sometimes two PDFs belong together page by page rather than one after the other. The classic case is a double-sided paper document scanned on a scanner that only scans one side: you end up with one file of front sides and another of back sides, often with the backs in reverse order. Merging them would put all the fronts first. Alternate & Mix interleaves the pages instead — one from the first file, one from the second, and so on — so the combined PDF reads in the right order. It runs entirely in your browser, so your scans stay private.

  1. 1

    Add two or more PDFs

    For a double-sided scan, add the file with the front sides first and the file with the back sides second.

  2. 2

    Set pages per turn

    Choose how many pages to take from each file before switching to the next. The default is one.

  3. 3

    Reverse a file if needed

    Turn on Reverse order for a file whose pages run backwards, such as backs scanned from the last sheet.

  4. 4

    Check and download

    Review the resulting page order and total page count, then download the combined PDF.

Built for double-sided scans

Rebuild a two-sided document from a single-sided scanner in one step, with no manual reordering.

Order preview

See exactly which page lands where — like A1 B3 A2 B2 — before you create the file.

Private and fast

Pages are combined in your browser. Your documents are never uploaded.

Fixing double-sided scans

Feed the stack through the scanner to capture every front side, then turn the whole stack over and scan again. Because the stack is upside down, the last back side is scanned first, so the second file runs backwards: page 6, 4, 2. Add the fronts as file A and the backs as file B, turn on Reverse order for B, and the result alternates A1, B3, A2, B2, A3, B1 — which is pages 1 to 6 in order. If your scanner saved the backs in the normal order, leave Reverse off.

Taking several pages per turn

Pages per turn controls how many pages are taken from a file before switching. Take 2 from A and 1 from B to place a page after every two pages, for example inserting a blank notes page or a translation after each spread. With three or more files, the tool cycles through them from top to bottom, taking each file's number of pages per turn.

Files with different lengths

Files don't need the same number of pages. Alternating continues as long as every file has pages left; once one runs out, the remaining pages of the others are appended in order. The page count and order preview above the download button show the exact result before you create the file, so there are no surprises.

Alternate & Mix vs. Merge

Merge PDF places whole documents one after another, which is right for combining separate reports or chapters. Alternate & Mix weaves pages together, which is right when the files are two halves of the same document. If you need a custom order that follows no pattern, combine the files with Merge PDF and rearrange pages by hand with Organize PDF.

Pro tip: scanned the backs upside down? After mixing, use Rotate PDF to turn just the affected pages the right way up.

Frequently Asked Questions

How do I combine front and back scans into one PDF?

Add the PDF with the front sides as file A and the PDF with the back sides as file B. If you scanned the backs by flipping the whole stack over, they come out in reverse order, so turn on Reverse order for file B. The result alternates front, back, front, back in the correct reading order.

What happens if the files have different page counts?

Pages keep alternating while every file still has pages. Once a file runs out, the remaining pages of the other files are added at the end in their chosen order, so no page is ever dropped.

Can I take more than one page at a time from a file?

Yes. Set Pages per turn for each file. For example, take 2 pages from file A and 1 page from file B to insert one page from B after every two pages of A.

Can I mix more than two PDFs?

Yes. Add as many files as you need; the tool takes pages from each file in turn, from top to bottom of the list. Use the arrows to change which file comes first.

Is the quality of my pages affected?

No. Pages are copied as they are, not re-rendered or compressed, so text stays selectable and images keep their original quality.

Can I use password-protected PDFs?

Not directly. Remove the password with Unlock PDF first, then add the unlocked copy here.