The source code of each of the software components is available on their respective sites. For statistics on the source code (and other useful information), please see : Black Duck Open Hub
Some quick links to the various repositories:
ClearOS apps created to make it super easy to install, manage and configure the software components
The policy is to work closely with each upstream project to add / improve features there. See also: "Upstream First"
If you want to use WikiSuite (versus auditing and/or contributing to the source code), please see: How to install WikiSuite