OSMapTuner is a mobile editor for OpenStreetMap running on Androidbased smartphones and Tablet PCs. OSMapTuner is the first mobile editor that focuses on editing tags and tag values. OSMapTuner is designed to support specific onsite editing use cases which are not possible with current editors. OSMapTuner helps to add more details to the map, especially those details forcing mappers to be onsite, e.g. detailed tagging of roads, tagging of house numbers or tagging of additional attribute values. OSMapTuner increases the efficiency of OSM mapping.