Data and massive data collection increasingly define political and economic citizenship. Data infrastructure such as open data portals and data visualization platforms funnel citizen participation, capturing much of the contemporary imaginary of activists and ordinary users alike. The new forms information takes today—increasingly numerical and statistical—intervene to alter the ‘classical’ dynamics of citizen media, offering new opportunities but bringing about novel challenges, too. Meanwhile, new varieties of activism emerge in the fringes of the datafied society, such as data activism, civic tech activism, and freedom of information advocacy. This entry explores how and where non-commercial grassroots media and the related practices meet the so-called ‘Big Data’. It connects the current fascination of the social world for data and the emergent manifestations of ‘data activism’ with the notions of empowerment and the politics of daily life that are at the core of citizen media. It explores in particular the evolution of the notion of empowerment through data. Empowerment is here understood as the process through which individuals and groups, by taking active part in the actions that reshape their communicative processes, exercise control over their communication resources and messages. More specifically, empowerment results from the people’s active exercise of control over technologies, and the possibility to contest social codes, legitimized identities, and institutionalized social relations citizen media provide. This paper explores the ways in which these core feature evolves when grassroots communicators and media activists come into contact with data, data analysis and data visualization tools.