Tiki Wiki CMS Groupware (often called TikiWiki or just Tiki) is a wiki-based, free open source content management system developed using PHP and released under LGPL license. Tiki includes a lot of features that facilitate collaborative editing of content in addition to usual functionality like user creation system, permission system, alterable menus, customizable page layouts.
As opposed to other CMSs that are extended mainly by means of additional downloadable plugins, TikiWiki has all necessary modules needed built-in, therefore it has large codebase. Also note that you are able to disable these module if you do not need them.
Depending on configuration the system is capable to perform as Knowledge base, Collaboration website, Publishing site, Commerce site,Social networking platform, CRM, Office suite, E-learning platform.
If you are excited about endless customization possibilities that Tiki Wiki CMS Groupware gives you, you can easily switch from your current CMS to is using CMS2CMS.