Digital platforms have come under intense scrutiny from scholars, policy makers, regulators, and the general public for their immense and yet largely opaque influence on the social and economic sphere. This book advances value-form and social-form directions in Marxian theory, moving beyond mainstream economic reasoning that informs much of the debate. Digital monopoly platforms such as Google and Facebook are analysed in light of their profit seeking behaviour and monetary flows generated primarily through advertising and data commodification. Considering the unity of production and circulation the book argues that outputs are better understood as a collection of different types of social forms shaped by capital (pre, intermediate and final commodities) and as forms of public wealth (Copyleft Free Software, publicly financed science and research). The authors critically engage with Marxian theories that conceptualise user activities as forms of digital labour, with zero-price markets and critical legal theories, as well as with ‘internet exceptionalism’ in various forms. The role of regulation of production, especially of financial markets and monopolies is critically discussed with an empirical analysis of the development of GAFAM companies, Google’s mandatory reporting to the Securities and Exchange Commission, and of digital advertising of Google and Facebook. The book discusses contradictions of the capitalist mode of production, limits of ongoing reform initiatives, and alternatives to the logic of capital and commodity production on digital platforms.