Cuberite
A lightweight, fast and extensible game server for Minecraft
...By using C++ instead of Java, Cuberite reduces memory consumption and CPU overhead while still allowing players using the standard Minecraft Java Edition client to connect and play. The software recreates core gameplay systems such as world generation, multiplayer networking, and commands while allowing extensive customization through a plugin system. One of its defining features is a Lua-based plugin API that allows developers to easily extend the server with custom features, commands, and gameplay mechanics. Cuberite is designed to run on a wide variety of platforms including Windows, Linux, macOS, Android devices, and embedded systems.