I built it over the summer, funded it through Kickstarter and have slowly been building a nice little client base of recurring revenue. The code itself is open source so it's self-hostable and free, but we provide a quick one-line deploy hosted solution as well.
Probably the most fun bit has been trying to just remove the barrier of troublesome local installation for these kinds of things. Usually people go with PHP because you can just run it everywhere, but that still requires setting up apache/mysql somewhere. We use Firebase and Node, so were able to get the entire package installed through a downloadable app. I think we probably have the fasted installation available for this kind of thing.
I work on it mostly full-time, then design client sites with it on the side.