It also serves as a playground - on the right hand side you see a textual representation of the GraphQL schema which is implemented on the server and that you can query here. On the left hand side you can execute a GraphQL query and see the results of its execution.
It's available here:
This is just a small demonstration. It really gets interesting when you start to play with the schema on the server side. Fortunately it's pretty easy to do. Since it's a simple Play application using webpack, all it takes to start playground locally and start playing with the schema is this:
$ git clone https://github.com/sangria-graphql/sangria-relay-playground.git $ cd sangria-relay-playground $ npm install $ sbt run