Interleave PDF guide
Alternate pages from two PDF files into one document with the predictable order A1, B1, A2, B2.
What this tool does
Interleave PDF loads two readable PDF documents in the browser, copies their pages into a new file, and alternates between the sources. A page from PDF A is added first, followed by the matching page from PDF B. If one file contains more pages, its remaining pages continue in their original order after the shorter document is exhausted.
This arrangement is useful when two scans represent opposite sides of a stack. For example, a scanner may create one file containing fronts in normal order and a second file containing backs. It can also combine a question document with a separate answer or commentary document when each source has a corresponding page.
Interleaving is not the same as ordinary merging. A merge places every page from the first file before every page from the second. This tool alternates pages and keeps the internal order of both inputs. It does not inspect page content, rotate pages, reverse either input, or determine whether a back-side scan was captured in reverse order.
How to use it
- Choose PDF A and confirm its detected page count.
- Choose PDF B and confirm its detected page count.
- Verify that each file already has the correct internal order.
- Select Interleave PDFs.
- Download the result and check the page thumbnails from beginning to end.
If the back-side scan is reversed, reorder that PDF before interleaving. For duplex reconstruction, test with a small document first because scanner feed direction varies by device.
Benefits
- Alternates complete pages without rasterizing them
- Supports input files with different page counts
- Reports both input counts and the final output count
- Limits the combined output to 500 pages
- Processes both files locally in the browser
Review and limitations
Page copying usually preserves visible page content, but document-level features can change when pages are placed in a newly created PDF. Review bookmarks, named destinations, cross-document links, forms, embedded files, scripts, accessibility tags, and portfolios if they matter to your workflow. Do not assume that digital signatures remain valid; the new page sequence is a different document state.
The tool accepts two files at a time and always begins with PDF A. It does not compare sizes or automatically pair related pages. Mixed page dimensions remain mixed in the output.