Merge PDF
Combine PDF files into one. Drag pages to reorder them before merging.
Drop PDF files here or click to browse
Up to 20 files · Max 50 MB each · PDF only
Processed entirely in your browser · Never uploaded · Free forever
About Merge PDF
Combining PDFs is the most common reason people go looking for a PDF tool, usually because something has to be submitted as a single file — a scanned form plus its attachments, several invoices for one expense claim, or chapters that were written separately.
This merger works at page level rather than file level. Every page from every file you add appears as a thumbnail, and you drag them into the order you want before merging. That matters when the pages you need are interleaved: a two-sided scan often produces all the fronts in one file and all the backs in another, and merging them end to end gives you the wrong document.
Your file is opened by JavaScript running on your own machine and the result is written back to a download. Nothing is sent to a server, so there is no upload wait, no queue, and no copy of your document sitting in someone else's storage.
How to use it
- 1Drop your PDFs onto the drop zone, or click to browse. Add as many as you need in one go or a few at a time.
- 2Wait for the page thumbnails to render — larger documents take a moment, and the counter tells you how many are ready.
- 3Drag any page to move it. The order shown is exactly the order you will get.
- 4Merge, then download. The result is a single PDF containing the pages in that order.
Limits
- Files at once
- Up to 20
- Size per file
- 50 MB
- Accepted
- PDF only
- Pages
- No fixed limit
Worth knowing
- Merging copies pages as they are. Text stays selectable, links inside a page keep working, and image quality is untouched — nothing is re-encoded or flattened.
- A merged file is roughly the sum of its inputs. PDFs already store their images compressed, so combining four 2 MB files gives you about 8 MB, not something smaller.
- Bookmarks and form fields belonging to the original documents are not carried across. If the source PDFs have fillable forms you need to keep, merge them in a tool that preserves AcroForm data instead.
- Password-protected PDFs cannot be opened. Remove the password in your PDF reader first, then merge.
Frequently asked questions
Are my files uploaded anywhere?
No. The merge runs entirely in your browser using the pdf-lib library. The file never leaves your device, which is why it works with no account and why the speed depends on your own machine rather than our servers.
Can I reorder pages before merging?
Yes, and that is the main reason to use this rather than a simple concatenator. Every page from every file appears as a draggable thumbnail, so you can interleave two one-sided scans or move a signature page to the end.
Does merging reduce quality?
No. Pages are copied across without re-encoding, so text stays selectable and images keep their original resolution. The output is not compressed either, so expect the merged file to be about the size of its parts added together.
Why will my file not open?
The two usual causes are password protection and corruption. An encrypted PDF cannot be read without its password — remove it in your PDF reader and try again. A file that fails to open in other readers too is damaged at source.
Is there a limit on how many files I can merge?
Twenty files per merge, each up to 50 MB. There is no page limit, but very large documents take longer to render thumbnails because that work happens on your own machine.