Pick your PDFs, get one file back. Free, no page limit, no ads, no account. The merging runs here on your own machine, so nothing is uploaded — which also means it is fast, and it works offline once the page has loaded.
Two or more files · they stay on your device
As many as your machine can hold in memory. There is no cap on our side, because there is no server on our side to pay for.
Yes — files are combined in the order you choose them, so put them in the order you want before you start.
Page content comes across untouched: the text, the images, the way the page looks. The outline panel — bookmarks — does not. Those belong to the file they came from, and copying a page does not bring them along.
Not while it is locked. Open it in your usual reader, save an unlocked copy, and merge that one.
These all work the same way — in your browser. Most are free; the ones marked as needing a plan are not.