...It works on both the client and server and can be installed on servers without requiring clients to also have the mod. The mod is designed to be as minimal as possible in the changes it makes, and as such, does not modify the light model or interfaces of vanilla Minecraft. Because of this, Phosphor should be compatible with many Minecraft mods (so long as they do not make drastic changes to how the lighting engine works.) If you've ran into a compatibility problem, please open an issue.