You have an existing back-end or API in place and need an awesome user interface for it. You understand the need to have a responsive, fast and usable web part of your user experience.
React/Redux developers usually have in their stack:
ES7 with optional modules and features,
Webpack / Babel with JSX support,
npm, and more recently yarn for packaging.
Also, many React/Redux developers easily fit into React Native development, as the tools are very similar, only the interface is different.
Functional application design
creates readable, easily testable application logic,
state of the application is stored easily (seamless / offline experience) and browsed (history / undo),
prevents errors, as usual mutability issues of typical OOP design are greatly reduced.
We can also hire a developer to match your framework or preferred solution directly. However, aside from React or Angular, the pool of people to hire from is somewhat shrinking.