Does markdown rendering happen offline?

What is used to render markdown documents in Joplin? Does rendering happen offline only? I simply tried to turn off all internet access on my machine and Joplin still rendered my markdown documents.

Though I wonder if this was just a fallback and the default rendering uses anything that sends data from my system to some api or whatever that then does the rendering?

I am handling sensitive data and therefore need to be sure that when I choose to store data locally that at no point this data leaves my machine in any way.

It’s all offline.