That’s just the nomnomml demo website - the text is editable so that you can see live updates in the rendered UML diagram.
The underlying js library will render straight to an HTML canvas or to SVG from a Node.js program. You can run it from the command line if you want to.
The underlying js library will render straight to an HTML canvas or to SVG from a Node.js program. You can run it from the command line if you want to.