Alfresco Community (J2EE, ECM, WCM)
Apache Lenya
APLAWS+
Autonome CMS (PHP, GPL)
Barebones CMS (PHP, MIT)
Bitweaver CMS (LGPL, PHP)
Bluenog CMS (based on Hippo & JetSpeed)
Bricolage
Campsite (GPL, PHP,web publishing)
CMS Made Simple (PHP)
Composite C1 Web CMS (.NET, dual license)
Digitalus Web CMS (PHP, Zend)
Docebo CMS
dotCMS Open Source (GPL, Java)
DotNetNuke
Drupal
e107 (PHP, GPL)
Enano CMS/Wiki (PHP, GPL)
Entando Portal Community Edition (Java, GPLv2)
eXo Web CMS
eZ Publish
Far Cry
Hippo CMS (Java, Apachev2)
Hotaru CMS (PHP, Social Bookmarking, Etc.)
Jahia Community Edition (Java, GPL)
JBoss Nukes
jCore CMS (PHP, GPL, multi-sites)
Jease (Java, GPL, Simpl)
Jetbox CMS
Joomla! (PHP, forked from Mambo)
Kooboo (.NET MVC, Chinese project)
Lenya
Liferay (Java, Portal, Collaboration)
Magnolia
Mambo Server
Midgard Project
MMBase
MODx CMS (PHP/AJAX)
mojoPortal (.NET, WCM, Portal)
Mura CMS (ColdFusion, GPL 2)
ndCMS
N2 CMS (.NET, LGPL, CMS Framework)
OpenCMS
Orbis CMS (PHP, BSD, Simple)
Oxite (.NET)
Papoo CMS
PHPNuke
phpwcms
PHPWebsite
Pimcore CMS (PHP/Zend, BSD)
Pligg
Plone
PortalApp
PostNuke
Pressflow (high performance Drupal)
ProcessWire CMS (PHP, GPLv2)
Radiant (Ruby, MIT, Simple)
Refinery CMS (Rails, MIT, Simple)
Red Hat CCM
SilverStripe (BSD, PHP/LAMP)
Simple Web CMS
Sitellite
SPIP (GPL, LAMP)
Squiz MySource
TikiWiki CMS/Groupware (PHP, LGPL)
TYPO3 (PHP, GLP)
TYPOlight webCMS (PHP, LGPL)
Umbraco
XOOPS
Web Edition CMS (PHP, GPL)
WebGUI
Weceem CMS (Java, Groovy/Grails, Apache)
Xaraya CMS