Interleave PDF Pages
Interleave PDF Pages interleaves the pages of two PDFs, or the two halves of one, for double-sided scans, using pdf-lib in your browser with no upload.
A: Fronts (odd pages)
Choose the fronts PDF
Drop to openPDF file. Stays on your device, never uploaded.
B: Backs (even pages)
Choose the backs PDF
Drop to openPDF file. Stays on your device, never uploaded.
Leave this on if you flipped the whole stack over and fed it through again. Turn it off if the backs are already in order.
At a glance
- Accepts
- Two PDFs (fronts and backs) or one PDF with all fronts then all backs
- Outputs
- One PDF in front, back, front, back order, pages copied without re-encoding
- Where it runs
- Entirely in your browser, on your device
- What leaves your device
- Nothing - the file never leaves your device
- Limits
- No size or count cap; bounded by your device's memory
- Account
- Not required - there is no sign-up
- Price
- Free, with no watermark and no usage cap
- Made by
- Visrut
- Last updated
- 11 November 2026
Interleave PDF Pages puts double-sided documents back together after a one-sided scanner. Scan all the fronts, flip the stack, scan all the backs, then add both files here and get one PDF in the right order: front 1, back 1, front 2, back 2. The backs can be reversed, since a flipped stack comes through last page first. It also works with a single PDF that holds all the fronts followed by all the backs. Everything runs in your browser with pdf-lib.
How to use it
- Choose Two PDFs, or One PDF if fronts and backs are in the same file.
- Add the fronts file and the backs file.
- Leave "Backs were scanned last page first" on if you flipped the stack; turn it off if the backs are already in order.
- Check the new order shown, then click "Mix & download PDF".
Frequently asked questions
Is my PDF uploaded?
No. Pages are copied with pdf-lib in your browser. Your files stay on your device.
Why would the backs be in reverse order?
When you flip a scanned stack over and feed it through again, the last sheet's back comes out first. Reversing fixes that so each back lands after its own front.
What if the two files have different page counts?
Pages are alternated while both files have pages, then the rest of the longer file is added at the end. A notice tells you when the counts differ.
How does the one-file option split the pages?
The first half of the file is treated as fronts and the second half as backs. With an odd page count the extra page counts as a front.
Does it change page quality?
No. Pages are copied as they are, not re-rendered or recompressed.