Merge PDF
Combine several PDFs into one. Your files never leave your device.
Runs on your device. The file is never uploaded.
Merge PDF joins several PDFs into a single file, in the order you dropped them: every page of the first file lands before any page of the second. The output is named merged.pdf unless you change it. Bookmarks and form field definitions live on the document, not the page, so the merge drops them.
Questions
What order do the PDFs end up in?
The order you dropped them in. The files list on the page is the order used, top to bottom, and each document contributes all of its pages before the next one starts.
Is there a limit on how many PDFs I can merge?
No fixed limit. Every file is held in your browser's memory while it merges, so the practical ceiling is your own device, a few hundred MB of PDFs is unremarkable on a laptop, and a phone will give up sooner.
Does merging re-compress or degrade the pages?
No. Pages are copied across as they are, with their existing fonts and images intact. The merged file is usually close to the sum of the inputs, merging is not a compression step, and if you want one, run Compress PDF afterwards.
Can I merge a password-protected PDF?
Not while it is still encrypted. Run Unlock PDF on it first with the password you have, then merge the unlocked copy.
What happens to bookmarks, form fields and annotations?
Page content, including annotations attached to a page, is copied. Document-level structure that does not belong to any one page, the outline (bookmarks) and the AcroForm field catalogue, is not carried into the new document, because the new document is built page by page.
Does Merge PDF upload my files?
No. It runs in a Web Worker in this tab using pdf-lib, and nothing is sent anywhere. You can watch the request counter on the homepage stay at zero while you use it, or turn off your network and merge anyway.