Merge PDF files into one
Combine several PDFs into a single document, in whatever order you choose, without the files ever leaving your device. The merging is done by qpdf compiled to WebAssembly running inside this page, so a stack of invoices, contracts or scanned letters stays on your machine. Each file is opened as you add it, so you see its page count up front and any file that cannot be read is named before you merge.
Drop your PDFs here
or
Your files are opened in this page only — they are never uploaded.
Your merged PDF is ready
DownloadHow to merge PDF files
Drop in two or more PDFs, put them in the order you want, and press Merge PDFs. The pages are joined end to end in the order shown on screen, so the first file's last page is followed by the second file's first page. The numbered badge on each row is the position that file will take in the result.
Order can be changed by dragging a row, or with the arrow buttons on it. The arrows exist because dragging does not work on a phone — the browser's drag events simply do not fire on a touchscreen — so on mobile the arrows are the way to reorder, not a fallback. Sort A–Z orders by filename the way a person would, so scan-2.pdf comes before scan-10.pdf rather than after it.
Why your files never leave your device
The merging is done by qpdf, a long-standing open-source PDF tool compiled to WebAssembly and running inside this tab. Your PDFs are read into the page's own memory, joined there, and handed back as a download. Nothing is uploaded, so a stack of invoices, contracts or scanned letters stays on your machine.
Once the engine has loaded, the tool keeps working with the network switched off entirely — which you are welcome to test, and is the clearest demonstration that the files are not going anywhere.
Each file is checked as you add it
When a PDF is added it is opened straight away to read its page count. That is why the page total appears before you merge anything, and it also means a file that cannot be read is marked at that moment, by name, with the reason next to it.
The common reason is a password. A PDF that needs one to open cannot be merged until the password is removed, which the PDF password remover on this site will do. A PDF that only restricts printing is different — it opens without a password, so it merges normally, though those restrictions are not carried into the merged file.
What merging does not keep
Page content, fonts, images and page sizes all survive the merge intact. Pages of different sizes stay at their own sizes — an A4 scan and a US Letter form can sit in the same document, each keeping its own dimensions.
Some document-level extras are dropped rather than merged: bookmarks and the outline tree, form fields and their values, attachments, and any existing encryption. This is worth knowing before you merge a filled-in form — the pages will look right, but the values may no longer be editable fields. If a document's bookmarks matter, keep the original alongside the merged copy.
Frequently asked questions
How do I merge PDF files without uploading them?
Use the tool at the top of this page. The merging is done by qpdf compiled to WebAssembly, which runs inside your browser tab, so the PDFs are read into the page's memory and never sent to a server. Once the engine has loaded the page keeps working offline.
Is there a limit on how many PDFs I can merge?
You can merge up to 30 files at once, up to 100 MB each and 200 MB in total. The limits are there because everything is held in your browser's memory. If you have more than that, merge them in batches and then merge the results.
Can I change the order of the files?
Yes. Drag a row to move it, or use the up and down arrows on each row. There are also buttons to sort by filename A–Z or to reverse the whole list. The numbered badge on each row shows the position that file will take in the merged document.
Why can I not drag the rows on my phone?
Native browser drag-and-drop does not fire on touchscreens. That is why every row also has up and down arrow buttons — on a phone those are the way to reorder the list.
Why is one of my PDFs marked as a problem?
Each file is opened as soon as you add it, so a file that cannot be read is flagged straight away with the reason. Usually it needs a password to open, in which case remove the password first with the PDF password remover on this site. The other causes are a damaged or partly downloaded file, or a file that is not really a PDF.
Does merging keep bookmarks and form fields?
No. Page content, images, fonts and page sizes are kept, but document-level extras are dropped: bookmarks and the outline tree, form fields and their values, attachments, and any existing encryption. Keep the original files if those matter to you.
Can I merge PDFs of different page sizes?
Yes. Each page keeps its own size and orientation, so an A4 scan and a US Letter form can sit in one merged document without either being stretched or cropped.
Is the merged file's quality reduced?
No. Merging copies the existing page objects across without re-encoding anything, so images and text are byte-for-byte what they were. Nothing is recompressed and no quality is lost.