Hi, co-founder of Kantree here. We were not the one submitting and hadn't plan this for today but we're here to answer any questions you may have :)
It's pretty classical stack with Python + Postgres + Redis on the backend and Angular.js for the frontend.
If I may also ask, how did you fund it, and what's your revenue model? I'd like to make the leap one day to having some SaaS revenue, but all the apps I've seen seem (on the surface at least) like pretty hard markets to stand out in...
We're is a worker cooperative, 100% bootstrapped (http://digicoop.io). We expect most of our revenues to come from Kantree.
BTW have you read http://www.reinventingorganizations.com/? It's very pertinent to the kind of organisation you've built according to your team page. I'd be interested to hear your thoughts if you have.