Technology-driven experiments—techno-experiments—have become a central mode of spatial intervention in a paradigm of smart growth. They are often considered a manifestation of a techno-managerial approach to governance, built upon the increasing influence of IT corporations on urban politics. Yet, there is little evidence indicating how these interests articulate techno-experiments and shape their legacies over the long run. This paper questions the varied politics of techno-experiments by comparing four projects in Stockholm and Amsterdam: two smart energy grid pilots and two online community-based platforms. Mobilizing the notion of the “social appraisal of technology,” it argues that techno-experiments can take different forms depending on how the role of digital technology is defined and negotiated by actors throughout the process of experimentation. The paper empirically shows that experiments can evolve in two main ways, defined as “whirlpools” and “mosaics.” As whirlpools, they upscale self-referentially; as mosaics, they instead extend into a set of scattered spin-offs. The key factors producing such outcomes, these cases show, are the form of partnership established at the outset of techno-experiments, and the ability of research funding and governmental agencies to steer projects as they develop.