https://github.com/skypjack/entt
Consider this list a work in progress as well as the project. The whole API is fully documented in-code for those who are brave enough to read it.
One thing known to most is that
EnTTis also used in Minecraft.
https://www.youtube.com/watch?v=D4hz0wEB978
https://github.com/skypjack/entt/wiki/Entity-Component-System#crash-course-entity-component-system
https://github.com/skypjack/entt/wiki/Events,-signals-and-everything-in-between