Sharing spare resources on C2C web platforms yields economic advantages for users on both supply and demand sides. It also increases resource efficiency by enabling better utilization patterns, which in turn provides societal and environmental benefits. Establishing trust among users is a key factor in facilitating the sharing of resources in such platforms. Among other methods, the use of profile pictures has proven to increase trust in peer-to-peer interactions. However, this comes at a considerable cost of privacy. In this study, we compare different levels of user representations (i.e. picture humanization) in a lab experiment involving 216 users and analyze their effect on users’ sharing behaviour on a C2C platform. Our results indicate that an increased level of picture humanization increases users’ perception of social presence and decreases their perception of anonymity. In turn, perceived anonymity has a marginal negative impact on users’ sharing behaviour while perceived social presence impacts positively users’ sharing behaviour through a path that involves trust and perceived reciprocity.