This Spark sample application is a Rapid Response Kit built by Twilio that enables aid workers to communicate immediately with a large group of volunteers in disastrous situations. The app uses the Twilio Java library to generate TwiML responses for conference calls, moderated conferences, and voice broadcasts. The application allows users to create conference numbers, join or connect to conferences, broadcast messages to phone numbers, and record new messages. The code is written in Java and utilizes Spark as a web framework.