I was disappointed with all the current state management solutions. Then I found mobx-state-tree, which seemed like a godsend to me (ok not really, but I liked the concept), but it was pretty big in terms of file size (mobx alone is big: 16.5kB). So I thought it's surely possible to make a smaller version of it, that's how this started. And after 2 failed attempts I can finally say: Here it is in all of its "glory". Note: This library uses Proxies and Symbols. Proxies cannot be fully polyfilled so you have to target modern browers which support Proxies.