Felsentaube is an offline-first field map for laying out alignments. Routes are recorded in the field vertex by vertex – from the crosshair at the centre of the map or straight from the device's GPS fix – and stored as GeoJSON.

The map is built on MapLibre with switchable basemaps, 3D terrain and elevations, from which the slope distance of a route is derived. Besides the internal GPS, external NMEA receivers can be attached over Bluetooth. The app and every map tile already viewed are cached, the routes live in the device's local storage: no network, no account, no server.

Sharing works by QR code, by link – the route travels inside the link itself, because there is no server to put it on – or as a GeoJSON file for further processing in QGIS.