Koota

Flecs

SanderMertens/flecs

Popular

Fast, lightweight C/C++ entity component system with relationships, queries and a web explorer.

EnTT

skypjack/entt

Popular

Header-only C++ ECS library known for speed; used in Minecraft (Bedrock) and many engines.

Unity DOTS

unity.com

Unity's data-oriented stack: Entities, the Burst compiler and the C# Job System for large-scale games.

Bevy ECS

docs.rs

Bevy's standalone ECS crate, usable outside the engine for ergonomic data-oriented Rust code.

bitECS

NateTheGreatt/bitECS

Tiny, high-performance ECS for JavaScript/TypeScript built on typed arrays.

Arch

genaray/Arch

High-performance archetype-based ECS for C#/.NET, popular with MonoGame and Godot C# developers.

LumixEngine

nem0/LumixEngine

3D C++ Game Engine - yet another open source game engine