bitECS

At ~5KB minzipped with zero dependencies, bitECS adds negligible overhead, crucial for web-based games where performance and load times are critical.

Supports both Structure of Arrays (SoA) and Array of Structures (AoS) patterns, allowing developers to optimize for cache efficiency or code readability, as shown in the example with Position and Velocity components.

Built with multithreading in mind, enabling efficient shared state management in concurrent applications, with dedicated documentation for multithreading scenarios.

Includes serialization support out of the box, simplifying state persistence for games or simulations, as highlighted in the Serialization docs.