mobx-state-tree (https://mobx-state-tree.js.org/)

Benefits of it over mobx is data normalization with references and JSON patches which allow you sync complex state easily. Typed models are also a plus.

Drawbacks are performance (see https://github.com/mobxjs/mobx-state-tree/issues/1267).

Previously was using immer, which I loved because of immutability but moved off since classes and OOP didn't feel as natural as in mst.

If I were to pick an alternative, might try redux with normalization https://redux.js.org/usage/structuring-reducers/normalizing-....

And if I were to build a state management tool, I would prioritize a library that has - immutability - JSON patches and snapshots - data normalization with references - schemas / models compatible with zod