Flecs
A fast entity component system (ECS) for C & C++
... every frame. Supports entities with hundreds of components and applications with tens of thousands of archetypes. Automatic component registration that works out of the box across shared libraries/DLLs. First open-source ECS with full support for Entity Relationships! Write free functions with queries or run code automatically in systems. Compiles warning-free on 8 compilers on all major platforms, with CI running more than 4000 tests.