Kandan is free to use open source web chat app developed by cloud foundary, a popular PaaS (platform as a service) provider. It is written in Ruby on Rails framework (A popular ruby language framework).
Kandan has really cool features and beautiful interface. It enables to manage multiple chat rooms simultaneously, easily share images, youtube links, etc. It supports collaborative team chat, file uploads and shared chat room audio. It has built-in emoticons and synchronized sound player. The app can be easily deployed to CloudFoundry, Heroku, dotCloud, or other PaaS provider by their command line tools.
You can play any audio-tag compatible url for the whole chat room. Images and youtube videos has embaded format supports. Kandan is licensed under AGPL and also a Custom licence can be obtained if you want more more features beyond the standard app features.