Alternate Merge
Merge PDFs by alternating pages. Combine front and back scans into one document.
About This Tool
Alternate Merge combines two or more PDFs by taking one page from each in turn: page 1 of the first file, page 1 of the second, page 2 of the first, and so on. It is made for a stack of paper scanned in two passes, the fronts in one file and the backs in another.
The files are used in the order of the list, which you change by dragging or with the arrows. Tick "Reverse second document" if the backs were scanned last page first; only the second file can be reversed. When one file runs out, the pages left in the others follow in the same order. The result is a new document: links on the pages are kept, but bookmarks, form fields that can be filled in, attached files and the document's properties are not carried over.
Everything happens in your browser; the files are not uploaded.
How to Use
Add the PDFs
Add the PDF with the front pages first and the PDF with the back pages second. More than two files can be added, up to 10 at a time.
Check the Order
Check that the files are listed in the right order, and tick "Reverse second document" if the backs were scanned from the last page to the first.
Merge and Download
Click "Interleave PDFs", then "Download". The file is saved as interleaved.pdf.
Use Cases
Duplex Scanning
Combine separately scanned front and back pages.
Document Assembly
Interleave pages from two related documents.
Book Scanning
Combine odd and even page scans into complete books.
Frequently Asked Questions
What if documents have different page counts?
Extra pages from the longer document are appended at the end.
Can I reverse page order?
Only for the second file in the list: tick "Reverse second document". To reverse the first file, or a third, put it through Reverse Pages first and add the result here.
Is this different from regular merge?
Yes, regular merge appends documents; alternate merge interleaves pages.