The Dgraph team is excited to make Ratel source available! The Ratel UI is the proprietary Dgraph data visualizer and cluster manager that powers the demo site https://play.dgraph.io. You can check out the Ratel source over on GitHub at GitHub - dgraph-io/ratel: Dgraph Data Visualizer and Cluster Manager.
Ratel is licensed under the Dgraph Community License and is not open source.
Any issues related to Ratel can be filed under the ratel repository.