How to merge PDF files
- Add your PDFs. Click the box above or drag files onto it. You can add files in several batches, for example from different folders.
- Set the order. Each file shows its size and number of pages. Use the up and down arrows to move a file, or the cross to remove it. The first file in the list becomes the start of the new PDF.
- Press Merge PDF. The pages of every file are copied, in order, into one new document.
- Download the result. The new file is named after the first PDF with "-merged" added, so it is easy to find.
What is kept when you merge
Merging copies whole pages without re-drawing them, so quality does not change. Text stays selectable and searchable, images keep their original resolution, and page sizes and orientations are kept, so you can safely combine A4 and US Letter pages or portrait and landscape pages in one file. Links inside a page usually keep working. Bookmarks (the outline panel), form fields that span several pages and digital signatures are not carried over, because they belong to the original document rather than to individual pages. If you need to keep a signed document valid, send it as a separate file instead of merging it.
Common uses
- Job and university applications: join a CV, cover letter and certificates into the single PDF many upload forms require.
- Invoices and receipts: combine a month of receipts into one file for your accountant or an expense claim.
- Scanned documents: phone scanning apps often save each page as a separate PDF. Merge them back into one document.
- Online sellers: put a packing slip, care instructions and a size guide into one printable file.
Tips
- Need only some pages from a file? Use Split PDF first to extract the pages you want, then merge.
- If the merged file is too big for email or an upload form, run it through Compress PDF.
- Have photos instead of PDFs? Convert them with JPG to PDF, then add that file here.
- Password-protected or restricted PDFs cannot be merged until the protection is removed. If you are allowed to, open the file and print it to a new PDF, then add the new copy.
How this tool works
This tool runs entirely in your web browser using two well-known open-source libraries: pdf-lib, which creates and edits PDF files, and Mozilla's PDF.js, the engine Firefox uses to display PDFs. Both are hosted on our own site, so your browser does not contact any other service while you work. Because the files never leave your device, the tool works for private documents such as contracts, bank statements and ID scans, and it keeps working even on a slow connection once the page has loaded. Very large files depend on your device's memory: a modern phone can usually handle a few hundred pages, and a computer can handle much more.
Want the full explanation? Read our guide: How to merge, split and convert PDF files safely.
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Frequently asked questions
Is it safe to merge PDFs online with this tool?
Yes. The files are processed inside your own browser and are never uploaded to our server or any other service, so nobody else sees them. Closing the tab removes everything.
How many PDF files can I merge at once?
There is no fixed limit. The practical limit is your device's memory. Dozens of normal documents, or a few hundred pages, work well on most phones and computers.
Will merging reduce the quality of my PDF?
No. Pages are copied as they are, without being converted to images, so text stays sharp and searchable and images keep their resolution.
Can I change the order of the pages?
You can change the order of the files with the arrow buttons. To reorder, rotate or remove individual pages, open the merged file in our PDF Editor, or split the PDF first with Split PDF and merge the parts in the order you want.
Why does a file show an error when I add it?
The file is either damaged, not really a PDF, or protected with a password or security restrictions. If you know the password, remove the protection with Unlock PDF, or print it to a new PDF, and try again.