If you are looking for free administrative control for your own game rather than exploiting existing ones, these "Free Admin" systems are industry standards:

When a server runs on a paid admin system, it inevitably creates a caste system. The "Premium Admins"—often those who funded the server or purchased their rank—wield god-like powers, often abusing the complex toolset simply because they can. The tools become toys, and the server becomes a playground for the staff rather than the players.