Paste your pages one per line and get a correct sitemap.xml — duplicates dropped, invalid lines flagged, the XML escaped properly. No crawling: you know your pages better than a robot following links does, and your server never gets hammered for the privilege.
Set what you want and the result appears as you go. Nothing needs uploading because there is nothing to upload — you are describing what to make, not sending us anything.
Your browser does all the work locally, using your own operating system where randomness is involved. Nothing is requested from a server, so nobody else has a copy of what you made.
Take the result to your clipboard, or save it as a file. Nothing is kept — refresh the page and it’s gone, so take what you need before you leave.