Sell and Interest in a Scheduler that uses the Rest API

I’m in the middle for developing a schedule that will make calls to OpenHAB via the RestAPI to turn on and off my lights (Items). I have it working and am developing a web interface for it. I was wondering if developers are allowed to make and sell things that use the OpenHAB RestAPI. It will run on the same network as an OpenHAP server, in my case that is the my home network where my OpenHABPi Server is.

Post your thought, suggestions, and comments.