In open and higher education, digital technologies are increasingly used to enable flexible learning pathways and unbundle programs into separate courses. Whereas technologies have been praised for enhancing the flexibility of curricula, the implications of going digital have yet to be fully explored in curriculum studies. This article aims to critically investigate how an open education platform, OpenLearn, describes, prescribes, and enacts a particular form of curriculum. Rather than understanding platforms as passive tools for facilitating education, the article draws on theoretical and methodological ideas from science and technology studies (STS) to approach "curriculum" as a collection of socio-technical practices in which platforms play an active role. The findings of our analysis detail how networks of human and other-than-human actors are situated in a wider ecology and enact five curricular practices: prescribing, mobilising, enrolling, evaluating, and rebundling. We propose "platform curriculum" as a sensitising concept to investigate how technologies enable and constrain these practices instead of simply flexibilising them. With this article, we argue for the further adoption of STS in curriculum studies to disentangle the specific ways in which technologies, too, shape education.