It is shown that the process of digitalization of the information society, which is now a trend of world development, should be considered in the context of consumer, management and technological aspects. The conceptual model of interrelation of concepts of digital economy, which are associated with objects of digitalization, is described: digital transformation, cloud computing, information infrastructure, the digital platform, the integrated digital platform, platform economy, an ecosystem. These concepts are interpreted from the point of view of service-oriented architectures; properties of public service are described. Methodological and technological aspects of digital economy platforms design are considered in terms of open systems model, for which the main definitions and properties are given. The example of the OSE/RM open systems model shows the specifics of digital platforms related to their reorientation towards application industries. It is stressed that a feature of digital platforms is the fact that the platform becomes a provider of application platform services to external consumers. The tasks that the digital platform should solve in a new capacity are formulated.