For full details on EWD Lite, see:
It's Apache 2 licensed, and involves the installation of nothing but a Node.js module: look Ma! No more Mumps Code!
It can be used with VistA on Cache or GT.M systems, but can also be used to build new applications using InterSystems' free GlobalsDB database.
What's not to like? Get out your "JavaScript the Good Parts" and get developing :-)
Rob