Flooding remains the most widely distributed natural hazard in Europe, causing significant economic and social impact. Nowadays, availability of earth observation data generates fundamental contributions towards mitigation of detrimental effects of extreme floods. The technological advance allows development of online services able to process high volumes of satellite data without the need of dedicated desktop software licenses. The talk presents the data, the algorithms and the technologies used to develop such an online system that can use multi-scale satellite data, together with reference and in-situ information, to map the areas affected by floods and giving the users the possibility to inspect, process, analyze and validate the information. The platform, created by National Meteorological Administration of Romania, offers services based on Open Geospatial Consortium standards for data retrieval (WMS, WCS, WFS) and server-side processing (WPS, WCPS). The services were built using open source solutions such as GeoServer, OpenLayers, PostGIS, GDAL, rasdaman.