How to Merge Multiple PDFs Into One — No Install

Classic scenario: a client sends 5 attachments, you need one PDF for accounting. Or you scan a passport with your phone — every page separate. You don’t want to buy Adobe Acrobat, and online services forward files who-knows-where.

The fastest path in a browser

FileTools Merge PDF merges files right in your browser — nothing gets sent to a server, it all runs locally via WebAssembly. Drag your PDFs, reorder with mouse, click "Merge" and you’ve got one file. Works on phones too — 10-20 files takes seconds.

What to watch out for

- Order — after dropping, double-check pages are in the right sequence. Reorder by dragging.

- Size — merged PDFs can be a few MB heavier because they don’t compress. If output is too big, run it through compression after (most tools bundle both).

- Protected PDFs — if they’re password-locked, unlock first. Most online mergers won’t touch encrypted files.

Alternatives for power users

macOS: Preview — open first PDF, drag others into the sidebar → File → Export as PDF. Windows PowerToys has "Advanced PDF Merger". CLI option is pdftk, but that’s for the terminal crowd.

For 95% of use cases, an online tool works fine — FileTools never stores your files, which is safer than a random service from Google’s first page.