OSMapTuner is a mobile editor for OpenStreetMap running on Android-based smartphones and Tablet PCs. OSMapTuner is the first mobile editor that focuses on editing tags and tag values. OSMapTuner is designed to support specific on-site 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 on-site, e.g. detailed tagging of roads, tagging of house numbers or tagging of additional attribute values. OSMapTuner increases the efficiency of OSM mapping.