esoTalk is free, open-source Internet forum software written in PHP and MySQL. It is intent on being extremely simple, fast, and modern, containing all of the essential features a forum might need, and a powerful plugin system allowing developers to extend it in any way they like.

esoTalk has been built from the ground up to take advantage of modern web technologies and provide the perfect balance between simplicity, power, speed, and scalability. It is released under GPL 2 License.

Requirements: PHP and MySQL
Demo: http://esotalk.org/
License: GPL License