Free Toolkit

PDF InterleaveInterleave pages from two PDF documents alternately.

PDF Interleave illustration
📄

PDF Interleave

Interleave pages from two PDF documents alternately.

How to Use
1

Upload Two PDFs

Drop PDF A (odd positions) and PDF B (even positions).

2

Interleave

Pages are alternated: A1, B1, A2, B2, etc.

3

Download

Get the interleaved PDF document.

What Is PDF Interleave?

The PDF Interleave tool combines two PDFs by alternating their pages. Page 1 from PDF A, then page 1 from PDF B, then page 2 from A, page 2 from B, and so on. If one PDF has more pages, the remaining pages are appended at the end. Perfect for reassembling double-sided scans where front and back pages were scanned separately, or combining two related documents page by page. Handles PDFs of different lengths gracefully.

Why Use Our PDF Interleave?

  • Perfect for reassembling double-sided scans
  • Handles unequal page counts gracefully
  • Simple two-file drag and drop interface
  • Maintains original page quality

Common Use Cases

Scanner Reassembly

Combine separate front/back scan batches into proper page order.

Comparison Documents

Alternate original and revised pages for review.

Bilingual Documents

Interleave translations with original pages.

Study Materials

Alternate question and answer pages.

Technical Guide

Uses pdf-lib to load both PDFs and create a new merged document. Iterates through pages using the maximum page count of either document. For each index, copies the page from document A (if available) then document B (if available) into the new document. Uses copyPages for faithful page reproduction. Handles mismatched page counts by including remaining pages from the longer document.

Tips & Best Practices

  • 1
    PDF A pages appear in odd positions (1, 3, 5...)
  • 2
    PDF B pages appear in even positions (2, 4, 6...)
  • 3
    Works with different page sizes between documents
  • 4
    For reversed back pages, rotate PDF B first

Related Tools

PDF Merge

Merge multiple PDFs.

PDF Tools

PDF Reorder Pages

Reorder PDF pages.

PDF Tools

PDF Split

Split PDF into parts.

PDF Tools

PDF Extract Pages

Extract pages from PDF.

PDF Tools

PDF Delete Pages

Delete PDF pages.

PDF Tools

PDF Rotate Pages

Rotate specific pages.

PDF Tools

Frequently Asked Questions

QWhat if the PDFs have different page counts?
Extra pages from the longer PDF are appended at the end.
QCan I interleave more than two PDFs?
This tool handles two PDFs. For more, interleave twice.
QDoes page size matter?
No, pages maintain their original sizes even if different between documents.
QCan I reverse the order?
Yes, swap which file you upload as PDF A vs PDF B.
QIs the interleave always 1:1?
Yes, one page from each PDF alternately.

About PDF Interleave

PDF Interleave is a free online tool from FreeToolkit.ai. All processing happens directly in your browser — your data never leaves your device. No registration required. No ads. Just fast, reliable tools.