The Temporary Storage Areas Design Optimiser Tool (TSA-DOT) is a decision-support tool that helps planners design and optimise nature-based flood management solutions. TSA-DOT provides practical guidance for incorporating temporary storage areas, such as ponds, wetlands, or raised field margins into flood risk management strategies to control runoff and reduce flooding. The tool's methodology and applications are detailed in a peer-reviewed paper published in the Journal of Flood Risk Management (link below), and both the tool and its source code are freely available on GitHub at https://github.com/martynr27/TSA-DOT.git. TSA-DOT is designed for flood risk professionals, catchment managers, environmental consultants, and researchers who need evidence-based approaches to sustainable flood mitigation.