Well, although helm is widely used in the kubernetes world, , it's still limited by it's nature as a cli tool. For nowadays, the standard way to extend kubernetes functionality is using CRD and the controller pattern. In Helm 3 's design doc, it talk about this kind of integration, but not a import one. So we create Captain to not only fill out our own needs, but to explore this kind of possibility for the community.
The first customer is oneself, of course. It's been widely used in our environment, and replace helm2/3 for the most cases. We also have a few of enterprise customers in China, they use REST API to integration captain to there systems. It works very well