GradeStack enable content owners to convert their content into interactive smart courses. These courses are then delivered to the learners through GradeStack Marketplace.
As GradeStack is cross platform, a user can buy a course on mobile device, study it on tablet and then take the full length test on a laptop using the same id.
Users data is stored on the cloud which gets synced across devices. Thus the user sees the same status of the content/reviews across devices.
GreadeStack has a great course creator tool which enable authors and publishers to add interactive widgets on top of their content. They can simply drag and drop widgets to make content more interactive. A few examples are Videos, Quizzes, Assessments, Flash Cards, 3D models etc.