Merge PDF files
Combine PDFs in the order you want. Nothing leaves your device.
100% Browser-Based — Files Never Leave Your Device
About Merge PDF
Pages are copied losslessly from each file into a single PDF, keeping text, images, links and page sizes intact. Because merging runs in a background Web Worker, even large documents won’t freeze the page, and you can cancel at any time.
How to merge PDF
- Drop two or more PDF files into the box, or click to choose them.
- Reorder the files with the arrow buttons.
- Click "Merge PDF" and download your combined file.
Frequently asked questions
Is it safe to merge PDFs here? Are my files uploaded?
Nothing is uploaded. PDFToolsFast runs entirely in your browser using JavaScript and Web Workers, so your files stay on your device. You can even disconnect from the internet after the page loads and the tool keeps working.
Is there a file size or file count limit?
There is no fixed limit. Very large jobs (several hundred MB) depend on your device memory.
Will merging reduce quality?
No. Pages are copied losslessly; text, images and links stay exactly as they were.
Can I merge password-protected PDFs?
Remove the password first with Unlock PDF (you need to know it), then merge.
Is it really free? Are there limits or watermarks?
Yes, it is free with no sign-up, no daily task limit and no watermark. Because your own device does the work, we have no per-file server costs to pass on.