Grassroots activism constitutes the backbone of civil society across political regimes. While many studies explored the role of social media and digital platforms in social movements, we focus on the ways local activists use these social media platforms to organize collectively against unwanted urban development. Localized (place-based) contention differs from large-scale social movements: it is less endowed with resources and it is directly related to physical space. We analyze 26 urban conflicts in six Russian cities based on 185 interviews with activists and experts to show how the residents leverage digital platforms’ affordances and argue that the former extensively rely on the latter for coordination, communication, and recruitment purposes. Yet, the nature of place-based conflicts makes blending online and offline organizational activities inevitable. We also demonstrate that despite their benefits, digital platforms also bring organizational challenges. The authoritarian state imposes further constraints, requiring activists to take into account state surveillance and repression in their engagement with social media. Our study contributes to the scholarship on digitally mediated actions, urging a reevaluation of social media’s role in local collective actions.