Need only a few pages from a large PDF, or every page in a separate file? You can do both here. Your file never leaves your device.
No — all the work happens in your browser, there is no server.
"1-3" means pages 1, 2, 3. "2,4,5" means only those three pages. You can also combine them: "1-2,5".
No — it must be unlocked first.
No — the pages come out exactly as they were, with no quality loss (this is a copy of the real pages, not a picture).