With the increasing use of web-based mapping applications, inter-mediation between public planning agencies and citizens is changing. This article investigates how one form of inter-mediation, geo-ICT-enabled apps (applications on mobile phones and/or internet that use maps or locations as basic references for any functional analysis), influences the degree of efficiency and participation in managing public space. The theoretical assumption here is that such apps encourage information disclosure and therefore have the potential to make a local government more responsive and transparent. Drawing on observation, interviews, and document and web content analysis conducted as part of a case study, this article suggests that the apps have indeed enhanced one municipality's response and have made citizens more active in uploading their complaints. However, unexpected and contradictory effects include an increase in trivial complaints, which has made the handling of reports less efficient, and the emergence of opportunistic behaviour by third parties on the basis of the complaints, which has made the services less effective. Consequently, the assumed causal relation between enhanced citizen participation and increased transparency and information disclosure requires an adaptation that incorporates such wicked effects.