Merge Two PDFs Together Page by Page
Weave two PDFs together page by page — ideal for merging front and back scans.
First PDF (odd pages)
Select the first pdf (odd pages)
Click to choose, or drop a file here
You can also paste (Ctrl+V / Cmd+V)
Most tools run entirely on your device
Second PDF (even pages)
Select the second pdf (even pages)
Click to choose, or drop a file here
You can also paste (Ctrl+V / Cmd+V)
Most tools run entirely on your device
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About interleaving two PDFs
Scanning a double-sided stack on a single-sided scanner typically produces two separate files — all the front sides in order, then all the back sides, often in reverse order since the stack gets flipped over. Interleaving weaves the two files together page by page, restoring the correct front-back-front-back reading order in one operation.
The tool takes two PDFs and alternates their pages into a single output with pdf-lib — page 1 of the first file, page 1 of the second, page 2 of the first, and so on — with an option to reverse the second file's page order first, for the common case where the backs came out of the scanner in reverse. Everything runs in your browser.
Supported files
Accepts two PDFs (fronts and backs). Produces a single PDF with their pages woven together in order.
Is my file uploaded?
No. Interleaving runs entirely in your browser with pdf-lib — nothing is uploaded.
How to Interleave PDFs
- 1
Add both PDFs
Drop the odd-pages file and the even-pages file into their slots.
- 2
Set the order
Tick the box if the second file was scanned back-to-front.
- 3
Interleave and download
Pages are woven A1, B1, A2, B2 … into one PDF.
Interleave PDFs — frequently asked questions
What's the classic use?+
You scanned the fronts of a stack, flipped it, scanned the backs — this merges them back into reading order.
What if the files are different lengths?+
Leftover pages from the longer file are appended at the end.
Is there a free way to weave two PDFs together page by page?+
Yes — this tool weaves the two files together entirely in your browser, free and with nothing uploaded.
Can I reverse the second file's order automatically?+
Yes — there's a toggle for that, since scanning the backs of a stack usually reverses their order compared to the fronts.
Do you upload my files to a server?+
No — every tool here processes your files entirely on your device, and nothing is uploaded to a server. The only exception is the AI tools, which send the extracted text (not the file) to Claude to do their work.
Is there a file size limit?+
There's no artificial limit we impose, but since processing happens in your browser, very large files (500+ MB or 1,000+ pages) are limited by your device's memory rather than by us.
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