This article analyses the main Spanish independent podcast networks. It is a two-phase qualitative study based on direct observation of the networks, a number of secondary sources and, especially, on semi-structured in-depth interviews with the coordinators or managers of these networks. From the political economy of cultural industries, the main objectives are to determine the motivation, perspective, and dynamics of these networks, as well as to explore their financial model. As podcasting implies cultural practices and meanings, we want to analyse whether independent podcast networks are basically a grassroots cultural production that maintain their amateur philosophy, or whether, in contrast, they are evolving towards an institutionalization that moves them closer to cultural industries and their practices, and the study of Spanish independent podcast networks is a useful starting point for putting mainstream and historical definitions to the test. This study sets forth how the progressive formalisation of podcast networks has generated tensions in the grassroots-industrialization balance. Spanish independent podcasters are pro-ams entering the production process of an industry in which other industrialized actors have already been established.