Pick a time in one zone and read it in as many others as you need — dates shown beside times, because the classic missed-meeting mistake is the day, not the hour. Your browser's own IANA database does the converting, so DST never lies.
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.
The answer appears on this page as you go. There is nothing to download, because the answer IS the page — screenshot it or write down what matters. Nothing is kept — refresh the page and it’s gone, so take what you need before you leave.