XO is a web interface to visualize and administrate your XenServer (or XAPI enabled) hosts.
It aims to be easy to use on any device supporting modern web technologies (HTML 5, CSS 3, JavaScript) such as your desktop computer or your smartphone.
XO is developped by Vates, a French company specialized in Open Source, and released under the AGPL v3 licence.
XO is evolving fast, so check the known bugs file first.
Documentation
Would you like to know more? Check this:
How to report a bug?
Xen Orchestra has three bugtrackers: one for the server, one for the interface and the last one for common issues or when you don't know to which part it is related to.