Yes, there are many CMS available for your website, most of them are Open Source. You can not only use them but may modify too according to your need but under GNU license. [...] Now move on to other PHP Based Open Source CMS, following list shows you 30 Open Source CMS besides WordPress which can be useful to build your website and manage your content.
Other content management systems that made their list include:
Each one on the list comes with a brief description of what it offers and where it comes from.