Urbanites increasingly turn to digital mobility platforms to make use of means of transportation and to plan and book journeys. While these platforms can contribute to making urban travel more sustainable and efficient, they can also lead to governance challenges and have negative external effects, raising questions about how public values can best be safeguarded. In this article, public values are defined as normative concepts that describe both the impact on and democratic control of an affected public. This article aims to initiate a more structured discussion about platform urbanism, specifically how and to what extent public values are incorporated in platform design and operation in the realm of mobility. It introduces an assessment framework for mobility platforms that was developed as part of a transdisciplinary research project in the Netherlands. This framework is grounded in two academic debates regarding 1) the rise of platform urbanism and 2) new forms of mobility that accompany the densification of cities. The paper refers to the mobility pilots Kutsuplus, UbiGo and Whim to illustrate how the safeguarding of public values can be evaluated. In the concluding section, the paper discusses some ways in which the assessment framework can be used for future research, for instance through scenarios.