How to Interleave PDF Pages
Alternate pages from two or more PDFs in one document in three simple steps. No software installation required.
Add Two or More PDFs
Select the PDF files you want to interleave, then drag them into the source order you need.
Choose the Page Order
Keep the normal cycle, reverse the source cycle, or reverse the pages in the second PDF for back-side scans. You can also choose how to handle different page counts.
Interleave and Download
Click “Interleave PDF,” preview the combined document, then download the finished PDF.
How Does PDF Interleaving Work?
The CompressFly PDF interleaver takes one page from each source file in turn. With files A, B, and C in the workspace, the default result is A1, B1, C1, A2, B2, C2, and so on. Reversing the cycle order changes each round to C, B, A; it does not reverse the pages inside those files. The separate “Reverse the page order of the second file” option reads only the second PDF from its last page to its first, which is useful when back-side scans were saved in reverse stack order. When the PDFs have different page counts, you can continue with the files that still have pages or insert blank placeholders for the missing turns. The pages are copied into one new PDF rather than rendered as page images. Everything is processed locally in your browser.
What "processed locally" means
- Your PDF files are not uploaded to a server
- Page ordering and PDF creation happen on your device
- PDF passwords are handled only in your browser
- The interleaved PDF is generated locally
Three Different Page Order Controls
Each control changes a different part of the interleaving sequence.
Drag the PDF Files
Dragging the files changes which source is treated as A, B, C, and so on.
Reverse the Cycle Order
This changes every round from A, B, C to C, B, A without reversing the pages inside a PDF.
Reverse the Second File
This reads only the second PDF from its last page to its first, which is useful for a back-side scan saved in reverse order.
Keep Going or Insert Blank Pages?
Choose what should happen when the source PDFs do not contain the same number of pages.
| When a file runs out | Keep Going with the Rest | Insert Blank Pages |
|---|---|---|
| Missing turn | The finished file is skipped | A blank placeholder is added |
| Output length | The total number of source pages | The longest PDF multiplied by the number of source files |
| Best for | Continuing naturally after a shorter file ends | Keeping every interleaving round aligned |
| Blank page size | Not applicable | Matches the first page of the first PDF |
No source page is discarded in either mode.
Why Use CompressFly to Interleave PDF Pages?
Easy to Use
Combine alternating PDF pages without wrestling with a general-purpose editor. The tool is built around this specific task, keeping the work straightforward.
Less Manual Sorting
Long documents are tedious to alternate by hand. Automatic interleaving saves the repeated page-moving work involved in building the sequence yourself.
Useful for Two-sided Scans
Separate front and back scans can become a document that reads in order. It is a practical way to bring a two-sided paper record back together.
One Coherent Document
Related pages can be read together instead of scattered across source files. The result is easier to review, keep, and pass on as a complete record.
Free in Your Browser
Interleave the files without installing specialist software or buying a PDF editor. There is no account or subscription requirement.
Private File Handling
Source documents stay on your device while the alternating copy is created. Interleaving runs locally in the browser, with no upload to a processing server.
Interleave PDF FAQ
How do I interleave PDF pages online?
Interleave PDF pages in three steps: 1. Add two or more PDFs and drag them into the required source order. 2. Choose the cycle order, second-file reversal, and unequal-page setting. 3. Click “Interleave PDF,” preview the result, and download the combined document.
What is the difference between interleaving and merging PDFs?
A standard PDF merge places one complete document after another, such as A1, A2, B1, B2. Interleaving takes one page from each source in turn, producing A1, B1, A2, B2. Use the Merge PDF tool when you want to append whole files instead.
Can I interleave more than two PDF files?
Yes. You can interleave two or more PDFs. With three files in list order, the result follows A1, B1, C1, A2, B2, C2, and continues until every source page has been used.
How do I combine front and back scanned pages into one PDF?
Place the front-side scan first and the back-side scan second. If the first PDF contains pages 1, 3, 5 and the second contains 6, 4, 2, enable “Reverse the page order of the second file.” The interleaved result will be 1, 2, 3, 4, 5, 6.
What is the difference between reversing the cycle and reversing the second PDF?
Reversing the cycle changes the source order used in every round—for example, C, B, A instead of A, B, C—but leaves each PDF’s internal page order unchanged. Reversing the second PDF reads only that file from its last page to its first.
What happens when the PDFs have different page counts?
Choose “Keep going with the rest” to skip a source after its final page and continue with the remaining PDFs. Choose “Insert blank pages” to add a blank placeholder whenever a shorter file has no page for that round.
Can I interleave only selected pages or page ranges?
The interleaver currently uses every page in each source PDF. If you need only selected pages, create smaller source files with the Extract PDF Pages tool before interleaving them.
Are PDF pages converted into images or reduced in quality?
Pages are imported into a new PDF rather than rendered as screenshots, so the tool does not intentionally lower page image quality. Because the document is rebuilt, review interactive forms, links, annotations, bookmarks, and digital signatures in the finished file.
Can I interleave password-protected PDFs without uploading them?
Yes, when you know the correct password. The file and password are handled locally in your browser. The result is a new PDF without the original password protection, so use the Protect PDF tool afterward if the downloaded copy should also require a password.