Regional landslide assessments and mapping have been effectively pursued by research institutions, national and local governments, NGOs and different stakeholders for some time; and a wide range of methodologies and technologies are proposed consequently. Land-use mapping and hazard event inventories are mostly created by remote sensing data, resulting in complications subject to accessibility and terrain. However, landslide data acquisition for the field navigation can magnify the accuracy of database and analysis. Analysing hazard patterns and triggering factors can take advantage of Open Source web and mobile GIS tools for an improved ground-truthing of critical areas. This paper reviews implementation of a secure mobile-map application called ROOMA (Rapid Offline-Online Mapping Application) for the fast data collection of landslide hazard and risk. This prototype assists for quick creation of landslide inventory maps by collecting information on the type, feature, volume, date and pattern of the landslide using Open Source web-GIS technologies for instance Leaflet maps, Cordova, GeoServer, Postgis and Postgres database. This application comprises of Leaflet map coupled with satellite images as base layer, drawing tools, geolocation (using GPS and Internet), photo mapping and events clustering. All the features and information are recorded into a Geojson file in an offline version (Android) and consequently uploaded to the online mode (using all browsers) with the availability of internet. Finally, the events can be accessed and edited after approval by an administrator and then be visualized by general public. ROOMA was tested for the collection of landslides in post-earthquake Nepal and can be applied as well for all other events and hazards such as floods, avalanches, etc.