The platform economy is growing exponentially while creating expectations for its potential to contribute to sustainable development. Despite this, most research studies have concentrated on well-known models such as Uber and Airbnb, dismissing platform alternatives. Thus, research aimed at showing the potential contribution of each platform’s business model to sustainable development is needed. Moreover, there is a gap in literature studying—thorough empirical research—to what extent platform cooperatives are an alternative to unicorn platforms in terms of working conditions. This chapter summarises the research performed in the PLUS project by Dimmons research group. It puts forward a framework to differentiate platform models, which considers governance, economic sustainability, technological and data policies, social responsibility, and external impact dimensions. This framework was tested with an empirical analysis of 60 platforms and a deep study of three alternatives to platform capitalism: Fairbnb, Katuma, and Smart. The research paper found that a sustainable design of a platform economy promotes sustainable development, and showed in what aspects the three platforms studied may be considered an alternative to unicorn platforms in terms of gender equality, work-life balance, and training opportunities.