Most "merge PDF" websites work by upload. You send your files to a server, it joins them, and you download the result. That is fine for a restaurant menu. It is less fine for a contract, a payslip or a scan of your passport, and it is no use at all on a plane.
Merging does not need a server. A PDF is a set of pages, and joining two of them is something a browser tab can do by itself, on your own computer.
The short answer
Open OpenPdfEdit in your browser once while you are online. After that the tab works without a connection. Choose Merge PDFs…, pick your files, put the pages in order and save a copy. The files are read from your disk and the merged file is written back to it. Nothing is uploaded, and you do not need an account.
Step by step
- Open openpdfedit.com/app. Do this once with a connection, so your browser can keep its own copy of the app.
- On the start screen, choose Merge PDFs… and pick the PDF that should come first.
- The app asks whether to include the document you have open in the merge. Choose Include it.
- Pick the other PDFs. You can select several at once. Their pages are added after the first file.
- A new document called
merged.pdfopens with all the pages in it. Open Pages to see them as thumbnails, and drag a thumbnail to move that page. - Choose Save a copy to save the merged file.
The merge makes a new document. The files you started with are not changed.
Using it with no connection
The first visit is the only one that needs the internet. To see this for yourself, load the app, turn off Wi-Fi and reload the page. The start screen still opens, and the steps above work the same way.
This is useful in two cases. One is the obvious one: a train, a flight, a hotel with bad Wi-Fi. The other is a document you are not supposed to send to an outside service at all, where an upload site is not an option even with a good connection.
How to check that nothing is uploaded
You do not have to take this on trust. Open your browser's developer tools (F12 on most keyboards), switch to the Network tab, and merge two files while you watch.
You will see the app's own files being loaded from openpdfedit.com. You will not see an upload, and you will not see a request to any other site. The PDFs go from your disk into the tab and back to your disk.
Getting the pages in the right order
Merging puts whole files one after another. Often that is not quite what you want: the signed page belongs at the end, or the cover letter should come first.
That is what the Pages panel is for. Every page of the merged document is a thumbnail there, and you can drag any of them to a new place before you save. There is more about rearranging, rotating and removing pages in organising PDF pages.
If the merged file is going to someone else, two other tools are worth knowing about. Password protection puts a password on the copy you send. And if you later need one part of the file back by itself, splitting is the same job in reverse.
If you would rather not use a browser
On a Mac, the Preview app that comes with macOS can also join PDFs: open one file, show the thumbnail sidebar, and drag the second file into it. Windows has no built-in way to merge PDFs, so there you need a tool of some kind.
FAQ
Can I merge PDF files without an internet connection?
Yes. Open OpenPdfEdit once while you are online so the browser can store the app. After that you can merge with the network switched off.
Are my files uploaded when I merge them?
No. The files are read and joined inside the browser tab, and the result is saved straight to your computer. You can confirm it in the Network tab of your browser's developer tools.
Does merging cost anything or need an account?
No. Merging is free and works without signing in.
Does merging change my original PDFs?
No. The merge creates a new document called merged.pdf. Your original files stay as they were.
Can I change the page order before saving?
Yes. Open the Pages panel and drag the thumbnails into the order you want, then save a copy.