Alternate and mix two PDFs into one
Scanners without a duplex feeder leave you with two files: all the fronts in one, all the backs in the other — often in reverse order. This tool interleaves them back into a correctly ordered document, taking one page from each file in turn, with the option to reverse the second file first. It runs in your browser, so scanned contracts and IDs never leave your machine.
How to alternate and mix two PDFs
Add both PDFs
Drop the fronts in the first slot and the backs in the second. Their page counts appear so you can sanity-check the pairing.
Reverse the second file if needed
Feeders usually spit the back sides out in reverse. Toggle 'reverse' and the last page of file two pairs with the first page of file one.
Mix and download
Press Mix. Pages are interleaved — 1A, 1B, 2A, 2B — and saved as one PDF in your browser.
What Alternate & Mix PDF can do
Duplex scans, fixed
Turn two single-sided passes into one correctly ordered document.
Reverse toggle
Handles the common case where the back sides come out backwards.
Uneven files handled
If one file is longer, its extra pages are appended rather than dropped.
Local processing
Scanned IDs and contracts stay on your device from start to finish.
Alternate & Mix PDF — frequently asked questions
How do I combine front and back scans into one PDF?
Load the fronts as the first file and the backs as the second, turn on 'reverse' if your scanner produced the backs in reverse order, and press Mix. You'll get a single document in the right order.
What if the two PDFs have different page counts?
Pages are interleaved until one file runs out; whatever remains in the longer file is appended at the end, so nothing is silently lost.
Do my PDFs get uploaded to a server?
No. Every tool on Notoo Tools runs as JavaScript and WebAssembly inside your browser tab. There is no server that receives your files — you can disconnect from the network after the page loads and the tool keeps working.
Do I need an account or a subscription?
Neither. There's no sign-up, no email, no free-tier limit and no watermark. Bookmark the tool and it opens straight into the work.