Privacy
Your text never leaves your browser. The conversion is JavaScript running on your own machine. This site is a set of static files on a CDN — it has no backend and no database, so there is nowhere for your text to be sent.
What is stored locally
Three things are kept in your browser's localStorage so the tool remembers where you left off: your conversion settings, your light/dark preference, and the contents of the input pane. All three stay on your device. Clearing your browser's site data removes them.
Third parties
This deployment loads Google Analytics for aggregate traffic statistics. Those scripts set their own cookies and are governed by Google's privacy policy. Neither has access to the contents of the converter panes.
Files you open
Uploading or dropping a .md file reads it with the browser's File API. The file itself is never transmitted.