Synthetic Aperture Radar systems are powerful observation tools for maritime surveillance applications such as fisheries monitoring or pirates detection and oil slick detection. It is an important problem that has not been completely solved. The Demonstrator of Maritime SAR Applications (DeMSAR) is proposed as an answer to these problems. It is an off-line implementation of a SAR image processor for detecting ships and/or oil slicks that provides two operation modes: an automatic processing mode for robust detection with default processing schemes and associated parameters, and a toolbox mode with different libraries conveying sets of algorithms designed for specific processing stages that can be configured by the user. The automatic processing scheme includes an edge detector, land mask estimation and a double parameter CFAR ship detector.