How to check that a browser converter is really local
Plenty of tools describe themselves as client-side. Three checks you can run in about a minute to find out whether one actually is.
Plenty of sites say "local" and mean "uploaded briefly." Three ways to check this one.
Watch the network tab
Open your browser's developer tools, switch to Network, and convert a drawing. The page and its scripts load. After that nothing goes out carrying your file. What you are watching is a Web Worker do the parsing on a background browser thread. That is also why the page stays responsive while a large drawing loads.
Then disconnect and do it again
Turn off your Wi-Fi and convert anyway. Nothing can leave a machine with no network. An export that still reaches your downloads folder was built locally.
There is no route that would accept it
There is no upload endpoint in the code, so there is nothing for a file to be posted to. The file stays in the tab's memory and goes away when you close it. Policies get quietly rewritten. Adding an upload endpoint means a commit.
What does get stored
Two cookies of our own: your terms acceptance and your language choice. Google Analytics and AdSense set their own, as on any ad-supported site, and the privacy page lists them. None of it touches the contents of your drawing.