School teachers’ work in the Nordics and elsewhere has become deeply affected by the ongoing school digitalization, through digital platform investments, digitalization reforms, and the pandemic situation. By focusing on how teachers’ work currently is shaped by emerging digital platform infrastructures, and how teachers’ themselves shape their digital work, this study aims to critically explore the implications of new platform ecologies. By drawing on a Swedish case project funded by Forte, we exemplify of how global commercial platform infrastructures have been integrated into and added to a highly marketized school system. While earlier studies critically approached school platform infrastructures mainly as managerial modes of governance, recent research has revealed its wider democratic implications for the public sector, e.g. the creating of technical lock-ins (Kerssens & van Dijck 2021). Based on a sociotechnical understanding of teachers’ digital work, digital platforms are not seen as simply ‘enablers’, but as agentic and carrying certain values alongside prescribed institutional uses that together regulate teacher work. Methodologically, trace and policy ethnography were used. First, we traced the digital work of four upper secondary school teachers (two men, two women) from two schools (one public municipal school, and one private consortia-owned school) via self-reported work activity time logs, followed up by focus group interviews, as well as a “go-along method”, for observing teachers’ online work. Lastly, we ‘moved out’ to trace the school and wider platform infrastructure from a national and international policy infrastructural perspective. Our preliminary results show how teachers operate within an institutional logic of bureaucratic, market and professional concerns (Friedson 2001) in their digital work, resulting in problems like work intensification and work-life imbalances. One related finding is also that different platform ecologies emerge across different private and public school forms. The dependence of global platform infrastructures in schools is currently increasing. This study hopefully can add a needed Nordic and critical dimension to how this affects teachers’ digital work.