(As long as you have fast internet) Codepen is so useful for making ui's... it massively smooths out the fiddling process and also convenient to share a ui with

(As long as you have fast internet) Codepen is so useful for making ui's... it massively smooths out the fiddling process and also convenient to share a ui with the debug / display mode or whatever it's called. I'm sure one could come up with a similar offline software for the creation aspect, but since it's hosted, it takes only two clicks to share a website demo, which seems like it would be hard to duplicate without cloud.