Merging looks trivial — and with the right tool it is. But three details separate a clean merge from a mess.
Rename files with numeric prefixes (01-cover, 02-contract) before merging, or use a tool that lets you drag files into order. In Kameleo you reorder in the merge list itself, and for page-level control the Page Editor lets you interleave pages from several documents visually.
A good merger copies each document's fonts and images once. Kameleo uses pdf-lib's copy mechanism, which preserves embedded fonts — your merged file looks identical to the sources.
Ten 5 MB scans make a 50 MB brick. Run the result through Compress (Strong level for scans) right after merging — in Kameleo both steps happen on your device, so there's no double upload penalty.
Kameleo never stamps a watermark on merged files and never uploads them — merging happens in your browser's memory. That's verifiable in your Network tab, not just a promise.