Cuberite is a Free and Open Source (FOSS) Minecraft-compatible game server. Cuberite is designed with performance, configurability, and extensibility in mind, and also aims to accurately recreate most Minecraft features. The server is written in C++, and there is an extensive plugin system that allows for the user to write their own plugins with Lua.
Cuberite was created in late 2010 by FakeTruth with its original name "MCServer", as a replacement for the vanilla Minecraft server. It was soon open-sourced and developers started contributing. Today, Cuberite is maintained by a large team of contributors and plugin developers.