No, it's run on a custom script called EpochTalk. Theymos paid a lot of Bitcoin to get this script built from scratch, and it will be open source later, which is quite generous of him.
Correction: Epochtalk is already open source.
Here's a link to the project on Github.Actually it's not completely open_source.You can check the readme file.You have to get accepted as a coder by the other contributers in order to contribute.
Epochtalk is an open source project and we are planning to accept contributions. If you would like to contribute to Epochtalk please email info@slickage.com.