We've started using Kong about 3 months ago and we're really excited about the way it helps us manage our APIs.
We've tried most of the community admin GUIs out there and although great contributions, they lacked some specific features we needed.
Features like multi-user administration and bulk consumer imports where essential to our needs.
Having that in mind, i decided to work on an open source GUI that provides some cool features that others might find helpful as well.
The GUI uses the awesome (imho) sails.js framework as a backend server, while the frontend it is built with angularjs.
You're most welcome to check it out and drop some thoughts :)