For users of the utility mod, Orion is a popular open-source combat-focused add-on.
The original version by developer GhostTypes has been discontinued. However, a continuation branch is currently maintained by the AntiCope community on GitHub. More about the orion add-on for Meteor.
Are you looking to install the for a Minecraft client, or are you interested in implementing the CMS into a web application project? AntiCope/orion: Continuation of GhostTypes' Orion - GitHub For users of the utility mod, Orion is
Drop-in solutions for file uploading and establishing relationships between database collections. For users of the utility mod