Merge PDF

What does the Merge PDF tool do?

The FreePDF Merge tool combines two or more PDF documents into a single PDF file. It preserves the full content of each PDF — text, images, vector graphics, hyperlinks, and page formatting — and concatenates them in the order you specify.

Unlike most online merge tools that upload your files to a remote server, FreePDF processes everything inside your browser using pdf-lib, an open-source JavaScript PDF library. Your documents are never transmitted over the internet.

How to merge

1. 1
   Add your PDF files

   Click the upload area or drag and drop your PDF files into the tool. You can add as many PDFs as you need in one session.

2. 2
   Set the merge order

   Drag the files up or down to arrange them in the order you want. The top file will become the first section of the merged PDF.

3. 3
   Click Merge PDF

   Click the Merge button. pdf-lib processes all the files in your browser — no waiting for uploads or server processing.

4. 4
   Download your merged PDF

   Once merging is complete, click Download to save the combined PDF directly to your device. No watermarks, no account required.

What FreePDF Merge PDF can do

• Merge unlimited PDFs in a single session
• Drag to reorder files before merging
• Preserves images, fonts, and vector graphics at original quality
• Works entirely in your browser — no file uploads
• No watermarks on the output
• Free, always — no account needed

Privacy — your files stay on your device

Merge PDF runs entirely inside your browser using pdf-lib and PDF.js (Mozilla) — open-source, audited libraries with millions of users. Your files are loaded into browser memory, processed on your CPU, and written back out as a direct download. Nothing is sent to any server — you can verify this in your browser devtools → Network tab. Close the tab and everything is cleared from memory.

Supported devices and browsers

Known limitations

FreePDF is honest about what it can and cannot do:

• Very large files (500MB+) may be slow depending on your device's available memory
• Encrypted or password-protected PDFs must be unlocked before merging
• PDFs with complex interactive forms may lose some form functionality after merging
• Digital signature certificates embedded in PDFs will be invalidated by the merge operation