[pja]

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.

[WesolyKubeczek]

I know it is editable, it's just inconvenient af to edit the text if the diagram is being drawn right over it.

[withinboredom]

you can move it out of the way.