Well, for, starters, Glitch is free for unlimited usage :)

Glitch is geared towards people collaboratively working on Node apps (it doesn't support anything else, unlike the other options).

However, it's much easier to get started, with an in-browser code editor, console, and starter projects.

I've been using Glitch to play around with ideas mostly and then I will build locally and deploy to something like Heroku. One other downside of Glitch is that source code is viewable by anyone, which means you probably don't want to launch a side project there.

Note: don't work for Glitch, Heroku, or anyone else mentioned