GetIt Hooks package, same as the mixin in
case you already use flutter_hooks.

Flutter state management for minimalists, by Suragch

Note:
  To learn more, watch this short Package of the Week video on the GetIt package:

MobX

A popular library based on observables and reactions.

MobX.dart, Hassle free state-management for your Dart and Flutter apps

Getting started with MobX.dart

Flutter: State Management with Mobx, a video by Paul Halliday

Flutter Commands

Reactive state management that uses the Command Pattern
and is based on ValueNotifiers. Best in combination with
GetIt, but can be used with Provider or other
locators too.

Flutter Command package

RxCommand package, Stream based implementation.

Binder