React.js in WHMCS
Buildig the Admin Interface / Client-Area with React.js more and more Applications are using it for example the PLESK Panel is build with it and it is very nice to work with.
Other Sites/Apps using React: Dropbox, Trello, nytimes, twitch, feedly, reddit, twitter.
I personally would like to see it in WHMCS! For people who are not familiar with React.js checkout some sites based on React in the browser they feel more like apps and are very fast.