Interleave PDF Pages

Merge odd and even pages from two PDFs into one perfectly ordered document. Built for duplex scans and one-click interleaving, completely free in your browser.

No adsNo signupNo file uploadsUnlimited use

File A — Front / Odd Pages

Drop or click

File B — Back / Even Pages

Drop or click

To interleave PDF pages means to alternate and merge pages from two separate PDF files into a single document in sequential order. The result is one PDF where page 1 comes from File A, page 2 from File B, page 3 from File A again, and so on. The most common reason people need this is duplex scanning: when you scan a double-sided document on a single-pass scanner, you end up with two separate PDFs — one with the front (odd) pages and one with the back (even) pages. OneClickPDF puts them back in order right in your browser. No files leave your device, no account is required, and there are no usage limits.

How it works

How to Interleave PDF Pages Online

Three steps. Upload your two PDFs, keep the reverse option on for duplex scans, and download a perfectly ordered document — all in your browser.

01
Step 1: Upload Your Two PDF Files
Add File A, which contains your front or odd-numbered pages, and File B, which holds your back or even-numbered pages. Drop each PDF onto its upload zone or click to browse from your computer or mobile device. Both files load directly into your browser's memory — nothing is sent to a server at any point during this step.
02
Step 2: Configure the Interleave Options
If your even pages were scanned in reverse order — standard on many flatbed and sheet-fed scanners — leave the Reverse File B option enabled so the back sides line up with their fronts. The tool automatically handles unequal page counts between the two files, so you do not need perfectly matched documents. A live result preview shows the exact page order before you commit.
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Step 3: Interleave and Download
Click Interleave & Download and your browser combines the two files on the spot — alternating one page from each in order. Download the finished PDF directly to your device. The entire process happens inside your browser, so your files are never sent to any server.

Why Use OneClickPDF to Interleave Pages?

A fast, private, and completely free way to combine two PDFs page by page — with the duplex-scan handling that most other tools leave out.

Reverse File B for duplex scans

Scanners often output the back pages in reverse order (last page first). Leave the Reverse File B option enabled and your interleaved PDF comes out in the correct reading sequence automatically. It is turned on by default because most duplex scans need it.

Unequal page count handling

File A and File B do not need to have the same number of pages. The tool alternates pages until one file runs out, then appends any remaining pages from the longer file at the end of the merged document.

Live result preview

Before you download, a preview shows the exact page order — A1 → B-last → A2 and so on — along with the total output page count and a note when the two files are unequal. You see precisely what you are about to get.

100% browser-based processing

Every operation happens locally in your browser using client-side JavaScript. Your files are never uploaded to any server, which means total privacy for sensitive scans, contracts, and records.

No limits, no account

There is no per-session cap on the number of files you can interleave, no hourly limit, and no sign-up. Open the tool and start working — no email address or subscription needed at any point.

No ads or interruptions

The tool runs cleanly without pop-ups, paywalls, or countdown timers disrupting your workflow. Upload, configure, download — and you are done.

Common Use Cases for Interleaving PDF Pages

The Interleave Pages tool fits a range of real-world workflows where two PDFs need to be combined page by page rather than appended end to end.

Duplex scanner output. Reassemble front and back pages from a two-pass duplex scan into a single properly ordered document.
Legal document collation. Combine exhibit front pages and their corresponding back reference pages before filing or sharing.
Academic packet assembly. Interleave questions from one file with answer keys from another for exam booklet preparation.
Book scanning projects. Merge odd and even page scans from a flatbed scanner into a correctly sequenced PDF manuscript.
Bilingual document pairing. Alternate between two language versions of a document, one page at a time, for side-by-side reading.

Why choose ours?

Fix duplex scans without uploading

Scanned front and back sides separately? Interleave them into the correct order — all in your browser, your files never leave your device.

Feature	Sejda	PDF24	iLovePDF	SmallPDF	Adobe	Ours
Dedicated interleave tool	✓	✓	✗	✗	✗	✓
Free & unlimited	✗ 3/hr	✓	—	—	✗ Paid	✓
Files stay in browser	✗	✗	—	—	Desktop	✓
No ads or interruptions	✗	✗	✗	✗	✗	✓
Auto-reverse for duplex	✓	✓	—	—	✗	✓
Unequal page handling	✓	✓	—	—	✗	✓
No file size limit	✗ 50MB	✓	—	—	✓	✓
No account needed	✓	✓	—	—	✗	✓

Competitor information was accurate at time of publication and may have changed.

Pages out of order, or just need to combine files end to end? merge your PDFs instead — or rotate, delete, and organize pages once they are interleaved. Every tool runs in your browser, no account required.

Frequently Asked Questions

What does it mean to interleave PDF pages?

Interleaving PDF pages means alternating and merging pages from two separate PDF files into a single document in sequential order. For example, page 1 comes from File A, page 2 from File B, page 3 from File A, and so on. This is most commonly used to reassemble front and back pages from a duplex scanner into a properly ordered document.

How do I combine odd and even PDF pages from a duplex scan?

Upload your odd pages PDF as File A (front pages) and your even pages PDF as File B (back pages). If your scanner outputs the back pages in reverse order, keep the Reverse File B option enabled. Click Interleave & Download and save the merged PDF. The tool runs entirely in your browser, so no files are sent to any server at any point.

What is auto-reverse for duplex scanning?

Auto-reverse — the Reverse File B option — corrects the page order of the back-page scan before interleaving. Many scanners output back pages in descending order (last page first) when scanned from the back of the stack. Enabling Reverse File B flips that sequence so the back pages match their front-page counterparts correctly before being merged. It is turned on by default because most duplex scans need it.

Can I interleave PDFs with different numbers of pages?

Yes. OneClickPDF handles unequal page counts between File A and File B automatically. The tool alternates pages until one file runs out, then appends the remaining pages from the longer file to the end of the merged document. You do not need to pad or split your files to make the page counts match — a live preview tells you exactly how many pages the output will have.

Is OneClickPDF Interleave Pages really free?

Yes, the Interleave Pages tool is completely free. There is no account required, no subscription tier, and no usage cap. You can interleave as many PDF files as you need in a single session without hitting any hourly or daily limits. There are also no ads or paywalls interrupting the process.

Do my files get uploaded to a server when I use OneClickPDF?

No. All PDF processing on OneClickPDF happens locally inside your browser using client-side JavaScript. Your files are never uploaded to any external server, which means they never leave your device. This makes OneClickPDF one of the most private options available for handling sensitive or confidential documents online.

What is the difference between interleaving and merging PDF files?

Merging PDFs appends one document to the end of another, so all pages from File A come first, followed by all pages from File B. Interleaving alternates pages between the two files, producing a result where page 1 is from File A, page 2 from File B, page 3 from File A, and so on. Interleaving is specifically designed for duplex scans and page-by-page collation.

How do I interleave PDF pages on Mac without installing software?

Use a browser-based tool like OneClickPDF. Open the Interleave Pages tool in any browser on your Mac, upload your two PDF files, configure the reverse option if needed, and download the merged result. No software installation is required. Everything runs inside the browser, including the PDF processing itself, so there is nothing to install or update.

What happens if File A and File B have different numbers of pages?

OneClickPDF handles mismatched page counts automatically. It alternates pages from both files until the shorter file runs out of pages, then appends any remaining pages from the longer file in order at the end of the merged document. No manual preparation is needed, and the result preview shows the final page order and count before you download.

Is there a file size limit for interleaving PDFs on OneClickPDF?

No. OneClickPDF does not enforce a per-file or per-session size limit for interleaving PDFs. Because all processing runs locally in your browser, the practical limit is your device's available memory rather than an arbitrary cap. There is also no restriction on how many files you can process per session, unlike some competing tools that limit free users to three tasks per hour.

Guides & tutorials

How to Interleave Pages From Two PDFs

Alternate pages from two PDFs — perfect for combining front and back scans into a single document. Free and private in your browser.

Combine Front and Back Scans Into One PDF

Scanned fronts and backs separately? Interleave them into the correct order — front 1, back 1, front 2, back 2. Free in your browser.

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