We are interested in Xenforo for a project, but we need SSO with Drupal, Moodle and a custom-made software of ours. SSO between these systems is annoyingly simple to do in Drupal, Joomla, Moodle and others, by using the CAS project - Central Authentication Server. http://en.wikipedia.org/wiki/Central_Authentication_Service We are able to make SSO work with ANY systems we build, in ANY programming languages we want. This already works between several systems like: Joomla: http://joomlacode.org/gf/project/auth_manager/ Drupal: http://drupal.org/project/cas Moodle: http://docs.moodle.org/20/en/CAS_server_(SSO) They all use the phpCAS library: phpCAS: https://wiki.jasig.org/display/CASC/phpCAS Is there any addon / internal support for CAS on XenForo? If not, may I suggest that you do this, as it would answer many SSO/integration requests?