React

React is a JavaScript library for making it easier to create user interfaces. It's the most popular library for this purpose at the moment. It's an open source project started by Facebook. The main advantages of the library are the steep learning curve, the countless available compatible libraries, the support of a huge company and it's great performance.

However, the main reason for choosing React is its flexibility. Since there is a mobile application for the project it's a huge advantage that React Native exists. It can be used to write native applications for Android and for iOS as well. All this while there is no need to learn a new technology since from a developer point of view everything is the same as developing for the web.