Satellite remote sensing is an effective approach to monitor floods over large areas, especially in regions where other information is lacking. But even so, challenges do remain. These include, but are not limited to, the required computation power and technical expertise to analyse this data. The HYDrologic Remote sensing Analysis for Floods (HYDRAFloods) tool presents a new scientific standard for surface water mapping. It can produce single sensor maps as well as daily data fused products into which all relevant sensors are combined. The system is under active development in SERVIR-Mekong and operational for near real time flood detection. HYDRAFloods embraces open science and combines relevant algorithms from literature with our own custom developments, published in open access journals. It uses cloud computing to facilitate data access and running at scale. The code is hosted on a repository with open source license. We’ll present the tool and its use cases. Track – Transition to FOSS4G Topic – FOSS4G implementations in strategic application domains: land management, crisis/disaster response, smart cities, population mapping, climate change, ocean and marine monitoring, etc. Level – 1 - Principiants. No required specific knowledge is needed.