Abstract‘[T]he “mainstream” of global governance has changed course’ and in so doing, might well have ‘outrun the standard tools of critical, progressive, and reform-minded international lawyers’, Fleur Johns wrote in 2019. It is especially the critical tools of ‘appeals to history, context, language [and] the grassroots’ in response to universalist planning that Johns sees absorbed in the turn to prototyping as a new ‘style’ of governance. In this article, we take on this observation and explore how the ‘lean start-up mentality’ (...) that Johns described has taken hold of tech-based climate governance. We base our reflections on the ‘Tech for Our Planet’ challenge that took place over 2021 and was showcased at the UNFCCC COP26 in Glasgow. While a turn ‘from planning to prototypes’ is observable, we question how exactly this ‘change of course’ affects the high modernist style of global governance and its critique by international lawyers. The ‘digital solutions for climate challenges’ that were showcased in Glasgow are indeed based on localized experiments with data science, thereby seemingly overcoming high modernist impulses towards universalist ideals. Yet, these experimental prototypes are developed with the ambition of being replicable and scaled up, to become a stack of tools deployable in any given scenario. This form of scaling up neither breaks with modernist aspirations based on technologically-mediated replicability—of moving the same logic inscribed in code to different sites and contexts—nor with a modernist understanding of knowledge as universal in its application. In our analysis, the determining feature is then not so much a matter of planning or prototyping in ideal type forms, but of replicability of knowledge production and scalability of technological know-how that underpin both planning and prototyping. Prototyping in the start-up space does not depart from, but rather reinscribes, a modernist representation of the human subject that forces its epistemological lens onto a world of nonhuman objects amenable to governance. Critical international lawyers’ toolkits must therefore be reconfigured with a focus on a governance style of disembodied knowledge production that runs through both planning and prototyping. (shrink)