What is alternate merge used for?

The most common use is reassembling double-sided scans. Many scanners only scan one side at a time. You scan all front pages first (1, 3, 5...) and then all back pages (2, 4, 6...), often in reverse order. Alternate merge with the second file reversed reassembles them into the correct page sequence.

What if the two files have different page counts?

If one file has more pages than the other, the remaining pages from the longer file are appended at the end. This handles cases where the last page of a double-sided document is blank or where you are combining documents of different lengths.

Can I reverse the second file's page order?

Yes. When scanning backs of pages, you often scan them in reverse order (last page's back first). The 'reverse second file' option handles this automatically, interleaving the pages in the correct sequence.

Is this different from regular merge?

Yes. Regular merge appends one file after the other. Alternate merge interleaves pages: A1, B1, A2, B2, A3, B3, etc. This creates a page sequence that combines content from both files in an alternating pattern.

Alternate Merge

Powerful Alternate Merge Features

Page Interleaving

Alternates pages from two files: A1, B1, A2, B2, creating a combined sequence.

Scan Reassembly

Reverse second file option for reassembling double-sided scans in correct order.

Private Processing

Documents interleaved locally in your browser. No server uploads.

How To Alternate Merge Online for Free

Upload Two PDFs

Drop your two PDF files into the tool. Both are loaded locally on your device.

Configure Interleaving

Choose whether to reverse the second file and preview the interleaved page sequence.

Download Merged PDF

Download the PDF with pages alternated from both source files.

Merge two PDF files by alternating their pages, interleaving page 1 from file A with page 1 from file B, then page 2 from A with page 2 from B, and so on. Essential for reassembling double-sided scans where odd and even pages were scanned in separate passes, combining answer sheets with question papers, or creating side-by-side comparison documents. Processing runs locally via WebAssembly.

Everything You Need in a Alternate Merge

Alternating Sequence

Pages interleaved from both files in A1-B1-A2-B2 order.

Reverse Option

Reverse page order of second file for back-to-front scan reassembly.

Flexible Lengths

Handles files with different page counts. Extra pages appended at the end.

Sequence Preview

Preview the interleaved page order before generating the final PDF.

Quality Preserved

Original page quality and text searchability maintained throughout.

Local Processing

WebAssembly interleaves pages on your device. Documents stay private.

Frequently Asked Questions

Document Work Made Easy

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