Plone alternatives

Plone
Plone is a free and open source content management system built on top of the Zope application server. In principle, Plone can be used for any kind of website, including blogs, internet sites, webshops and internal websites. It is also well positioned to be used as a document publishing system and groupware collaboration tool. The strengths of Plone are its flexible and adaptable workflow, very good security, extensibility, high usability and flexibility.
Plone alternatives are:
Drupal, SharePoint, Joomla, Alfresco