Type a title, a subtitle and your website, add a logo if you have one, pick a template — and download the 1200 × 630 image social platforms show when your link is shared. Drawn pixel-for-pixel on your own device.
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 finished file saves straight to your device. Nothing is kept — refresh the page and it’s gone, so take what you need before you leave.