Interleave the fronts and backs of a PDF
Does your scanner only scan one side? Scan all the fronts, flip the stack, scan the backs and they are put together here in the right order. Your files never leave your computer.
Select one or two PDFs
two files (fronts and backs) or one with all the fronts followed by the backs
How to combine fronts and backs scanned separately
Many scanners with a document feeder only read one side of the sheet. The usual fix is to scan twice — first the fronts, then the backs — and this tool puts the pages back in the order of the original document.
Select or drag two PDFs (fronts and backs) or a single one with all the fronts followed by the backs.
Check which file is which (you can swap them) and whether the backs are in reverse order; if the page counts don't match, choose whether to add blank pages.
Review the thumbnails of the final order, remove blank pages if you want and click Interleave pages to download the PDF.
What is interleaving PDF pages useful for?
Combining double-sided scans from single-sided scanners
Combines odd pages with even pages PDFs to reconstruct the complete document.
Reversing even pages scanned backwards
Interleaves correctly even if reverse pages were scanned in descending order.
Reorganizing double-sided contracts and questionnaires
Ensures exact correlation between front and back without manual sorting.
Saving hours of work on large scans
Generates the final ordered PDF in one click 100% privately in your browser.
Why use JapalTools?
Your files never leave your device
Everything happens in your browser. Documents are never uploaded to any server, so you can use it with payslips, contracts or ID documents.
Free, no sign-up and no watermarks
You don't need an account or to leave your email, and nothing is added to the result.
Works on any device
Computer, tablet or phone, with an up-to-date browser (Chrome, Edge, Firefox or Safari). Nothing to install.
Frequently asked questions
After the fronts, the stack comes out with the last sheet on top; when you flip it to scan the backs, the scanner starts with the back of the last sheet. That's why the “reverse order” box is ticked by default. If the result is out of order, untick it or try swapping the files.
Each page is drawn at low resolution in your browser and the share of dark ink is measured, ignoring the edges. If it doesn't exceed the maximum you choose, it counts as blank. The option is off by default and the list marks the pages that would be removed, so you can check before downloading.
No. The pages are copied as they are into a new PDF, without recompressing them: they keep their resolution, orientation and, if they had it, selectable text. The only thing that changes is the order (and any blank pages you choose to add or remove).
Yes. If one document has more pages than the other, remaining pages are appended at the end sequentially.
No. The document is processed in your own browser and is not sent to JapalTools or anyone else. When you close the page, no copy remains outside your device.