I use Scala, Play, Postgres for backend API. I started with checking Flask and learning Rails, but then I just switched back to the stack I am comfortable with

I use Scala, Play, Postgres for backend API. I started with checking Flask and learning Rails, but then I just switched back to the stack I am comfortable with as I don't want to learn both new backend and frontend (Angular.js) stuff on the project and focus on delivering. Frontend and backend code are kept separately for now and I use Yeomen for assisting frontend development and it works fine. If you go with Rails you can strip it down and check http://api.rubyonrails.org/ http://api.rubyonrails.org/ for APIs. There's similar project for APIs in Django.