Impromptu is built on Vertx, Java and Mongo. It was hosted on the cloud (Cloudbees). It was an exploratory project that aimed to rival Tinder with a question-answer format dating app.
This project is primarily a web server spun up using vertx's event and non-blocking architecture. It exposed a set of APIs for a front-end HTML5 client built on phoneGap to consume (project yet to be uploaded)