(I work at deployd) Yes, the cycle is funny. We don't usually focus on the GUI when talking about deployd; someone outside the company posted with this headline.
Open source was a no-brainer for us. There are some other key concepts that make it a compelling tool, particularly how easily extensible the platform is.
Jeff, has deployd considered adopting a JSON-based media type like Collection+JSON or HAL or JSON-LD (and there are others, or you could roll your own) so that the JSON APIs are properly RESTful?
(I work at Deployd) Our goal is first and foremost to generate useful APIs that you can use in your front-end, not necessarily to strictly adhere to the REST pattern. We do tend to use REST terminology when describing Deployd, and maybe that's a mistake that's causing more distraction than necessary.
Open source was a no-brainer for us. There are some other key concepts that make it a compelling tool, particularly how easily extensible the platform is.