How to merge PDF files
- Drop two or more PDFs into the box above, or choose them from your device.
- Drag the files, or use the arrows, to put them in the right order.
- Select Merge to combine them.
- Download merged.pdf.
Good to know
Password-protected PDFs can't be merged until the password is removed. To merge only some pages of a file, first use Split PDF to extract them, or rearrange the result with Organize PDF.
Questions
- Are my PDFs uploaded when I merge them?
- No. PDF-IO merges the files inside your browser with the open-source pdf-lib library. The PDFs never leave your device.
- How many PDFs can I merge at once?
- There is no fixed limit. Dozens of files work fine; the practical limit is your device memory.
- Does merging reduce quality?
- No. Pages are copied as they are, without re-rendering or recompressing images. If the merged file is too large, use Compress PDF afterwards.
- Are links, bookmarks and form fields kept?
- Page content and links to websites are kept. Bookmarks (the outline) and interactive form fields are not carried over, and links that jump to another page inside a document may stop working.
- Is a watermark added?
- No. PDF-IO never adds watermarks.