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FormatDrop
How-To Guide

How to Merge Multiple PDFs Into One

Combining multiple PDFs into a single file is a routine task — assembling a contract from signed pages, building a portfolio from individual documents, or merging scanned chapters into a complete book. Modern PDF tools handle merging without re-encoding, so quality is preserved exactly.

Step-by-step instructions

  1. 1

    Merge scans and images into one PDF with FormatDrop

    FormatDrop cannot merge files that are already PDFs yet. A PDF merge tool is coming soon. What works today: if your pages are scans or photos, drop the JPG or PNG files on the JPG to PDF converter. It joins them into a single PDF, one page per image, right in your browser. Free plan limits: up to 5 files, 10 MB each. Pro raises the size limit to 500 MB per file.

    Go to converter
  2. 2

    Merge files that are already PDFs with a free desktop tool

    On a Mac, open the first PDF in Preview, drag the other PDFs into the page sidebar, and save. On any system with a command line, qpdf is free: qpdf --empty --pages a.pdf b.pdf c.pdf -- output.pdf. Both keep every page exactly as it was, with no re-encoding.

  3. 3

    Check the merged PDF

    Open the result and confirm the pages are in the right order. Bookmarks and metadata from the first file are usually kept. Bookmarks from later files may be lost — re-add them in your PDF reader if you need them.

Why merge PDF files?

Merging PDFs is a one-of-a-kind operation that's universal in business — every contract, every report, every scanned book has been merged at some point. Doing it well preserves every byte of the originals.

Your files never leave your device

FormatDrop runs the conversion engine entirely inside your browser using WebAssembly. No file upload. No server. Nothing stored. You can verify this by opening DevTools → Network tab and watching: zero upload requests.

Frequently asked questions

Best command-line tool to merge PDFs?
qpdf: `qpdf --empty --pages a.pdf b.pdf c.pdf -- output.pdf`. PDFtk: `pdftk a.pdf b.pdf c.pdf cat output output.pdf`. Both preserve the original PDFs exactly without re-encoding.
How do I merge PDFs on a Mac?
macOS Preview: open the first PDF, drag additional PDFs into the sidebar, save as new PDF. Or use the command line: `"/System/Library/Automator/Combine PDF Pages.action/Contents/MacOS/join" -o output.pdf input1.pdf input2.pdf`.
Can I merge PDFs in Python?
Use PyPDF2: `from PyPDF2 import PdfMerger; merger = PdfMerger(); for f in ['a.pdf', 'b.pdf']: merger.append(f); merger.write('output.pdf')`. Or pypdf (the maintained fork).
Combine images into one PDF — Free

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