Guide · 2 min read
How to merge PDF files into one without uploading them
The most popular PDF sites upload your documents to their servers. Here is how to combine payslips, contracts or an ID into one file without them leaving your device.
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Merging PDFs is one of those chores that turns up at the worst moment: an application asking for “a single file with all documents”, an accountant wanting your last three payslips together, a bank needing both sides of your ID in one document. Nearly always, they are papers full of personal data.
The quick way
- Open Merge PDF.
- Drop all the files at once, or add them one by one.
- Put them in order with the arrows.
- Press Merge PDFs and download the result.
Pages are copied as they are, without recompression, so text stays selectable and images keep their quality. It all happens in your browser.
What happens to your documents on other sites
Most online PDF services work by uploading your files to their servers, processing them there and sending back the result. Their policies usually say the files are deleted after a few hours, and that is probably true. But in the meantime your payslip, contract or ID sits on another company’s computer, possibly in another country, exposed to its staff, its suppliers and any security failure it has.
You do not need to assume bad faith to prefer that it did not happen. It is enough that it is unnecessary: a modern browser can merge PDFs on its own.
How to check that nothing is uploaded here
You do not have to take this page’s word for it:
- Turn off your wifi after the tool has loaded and merge your PDFs. It works the same.
- Open your browser’s developer tools on the Network tab and merge a file. You will see no request carrying your documents.
- Read the code. Pseudononymous is free software and the code is published on GitHub.
Common problems
“It is password-protected.” An encrypted PDF cannot be read without its password. Open it in your PDF reader, enter the password and save an unprotected copy, then merge that.
The outline or bookmarks are gone. Merging copies the pages, not each original document’s navigation structure.
The final file is very large. Merging does not compress: the result weighs roughly what the originals add up to. If the destination has a size limit, send scans at a lower resolution or split the submission.
A privacy bonus
The merged PDF is created from scratch, so it inherits none of the originals’ properties: no author, which is often the real name of whoever produced it, no internal title, no creating application. If you only need to send part of a document, use Split PDF to extract the pages you were asked for.