Merging PDFs is one of the most common jobs with documents: a signed form and a scan of an ID, several invoices for one claim, or the chapters of a report. The usual way is to open a website, upload the files and wait for a link. For anything private, uploading is exactly what you may want to avoid.

This guide shows how to merge PDF files in your browser, so the files stay on your device. It covers the steps, how to fix the order and the pages, what the result will and will not keep, and what to do when something goes wrong.

Why merge without uploading

A merged PDF often contains the most sensitive pages you have, such as bank statements, identity documents and contracts. When a website merges them for you on its server, a copy of each file travels over the internet and sits on someone else's machine, at least for a while.

When the merge happens in your browser, your computer does the work and the files are never sent anywhere. The result is the same PDF with one less thing to worry about.…