Merging is the most common PDF job there is: a scanned contract in two halves, a report and its appendix, a stack of receipts for one expense claim. The order matters and the page sizes matter, and both are decided before you press the button rather than discovered afterwards.

Using it in three steps

1. 1 Drop two or more PDF files onto the box, or click to pick them.
2. 2 Check the order in the list. The arrows move a file up or down, and the output follows exactly this order.
3. 3 Press Merge, then download. The page count of the result is shown so you can check nothing was left out.

Mixed page sizes

A4 and Letter are close enough to look identical on screen and different enough to matter on paper. This tool keeps every page at its original size instead of forcing one format on all of them: stretching a Letter page to A4 would shift the margins, and printing it back would clip the edges. If you need a single uniform size, set that in your printer dialogue where you can see the preview.

Why nothing is uploaded

The documents people merge are rarely trivial: signed contracts, bank statements, passport scans, medical letters. This tool does the whole job with code running on your own machine, so there is no server copy to trust, to delete, or to leak. The practical proof is simple - turn off your connection after the page loads and the merge still works.