No account, no watermark, no upload

Paste a snippet, get a picture of it. There is no account to create and nothing to dismiss before you can start, and nothing is stamped onto what you export — if a mark appears on your image it is because you put it there. The two things that usually happen on somebody else's machine, working out the syntax colours and drawing the picture, both happen in this browser tab. You can check that rather than take it on trust: load the page, disconnect from the network, and everything keeps working. That matters more here than it would elsewhere, because the snippet worth showing someone is quite often the one you would rather not hand to a third party — a key, an internal name, a piece of work that has not shipped.