Decoupled Drupal also allows to create separate website and mobile application based on the same API:
So you can also use Drupal as backend for mobile applications too. It's not required to remove monolithic Drupal 8 frontend based on Views, Panels, Display Layouts modules, you can continue to use Drupal 8 frontend and include React library only for one page, for example search with Google map.
Modules for creating API are inclueded to Drupal core starting from version 8.x. So you can build your own backend API immediately after drupal has been installed.
In this course we will build API for Single Page Application (SPA) with lists of news, events and filters for them based on Drupal 8 and modules Webservices, JSON API, RESTful, Views and others.
Let's start to build our API based on Drupal 8!