At the Joint Research Centre (JRC), scientists involved in maritime situational awareness are confronted with a growing volume of data. Every day millions of ship positions from terrestrial and satellite receivers are gathered globally and in real-time, as well as optical and radar Earth Observation images, leading to a significant variety of data. To support the researchers, policy makers and operational authorities in their activities a analysis platform with WebGIS functionality has been developed with the aim of turning data into valuable information and demonstrating pre-operational tools for maritime awareness. The platform is mostly based on FOSS software and consists of a front-end visualization tool and a back-end analysis engine. Fusion algorithms provide the ability to integrate data from multiple sources on the fly. A series of tools provide predictive analysis, activity mapping, anomaly detection, and cross disciplinary information, to support maritime security and safety and to improve marine knowledge. The web application is developed using open source programming languages (e.g. Javascript, Python), frameworks (e.g. Django, Geoserver), and interchange data format (JSON) to enable researchers to seamlessly integrate ad hoc algorithms developed in scientific languages (e.g. R, Matlab). A case study will be presented, showing examples of how the WebGIS architecture can provide visualisation and analysis tools to support decision makers and scientific and operational actors in the fields of fisheries science, maritime spatial planning, and maritime surveillance.