Under possible risk of compound impacts of climate and anthropogenic changes, the Managed Aquifer Recharge (MAR) is envisaged to be an appropriate solution. Site suitability mapping is a crucial step in MAR project planning which requires various data, processing and GIS analysis. An automated web-based tool, named G-MCDA, is developed in this study for quick and efficient suitability mapping. G-MCDA integrates Google Earth Engine (GEE), Multi-criteria Decision Analysis (MCDA), GIS and web-based interface that allows automated data downloading, GIS data processing and suitability analysis using MCDA. G-MCDA has been tested in upper Ganga-Yamuna Doab region, India, for site suitability analysis. The application of G-MCDA shows that most of the area (82%) is under suitable category followed by very suitable (12%), and moderately suitable (5%). The suitable area is mostly flat agricultural lands with alluvium aquifer. A few patches of urban and sloping lands found to be moderately/low suitable for MAR.