That's not exactly true. This is hostable, just like PlantUML is, but PlantUML also hosts an instance, linked directly on their sidebar: https://www.plantuml.com/plantuml

I'm never in a position where I can use cloud-hosted stuff, sad to say. So everything is hosted in-house. Between that, ITAR, and the general red tape nightmare it's sort of a minor miracle anyone makes anything.

Having said that I really like this new JSONCRACK a lot, now that I've played with it a little.