The gleamviz computational tool, a publicly available software to explore realistic epidemic spreading scenarios at the global scale. The GLEAM Simulator system consists of the GLEAM Server and the GLEAMviz Client application. The GLEAM Server uses GLEAM as the engine to perform the simulations. This server runs on high-performance computers managed by the GLEAM project. The GLEAMviz Client is a desktop application through which users interact with the GLEAM Server. It provides a simple, intuitive and visual way to set up simulations, develop disease models, and evaluate simulation results using a variety of maps, charts and data analysis tools.