GLEAMviz is a disease modeling software that simulates the global spread of infectious diseases by combining real-world data on population, human mobility, and disease dynamics. It integrates high-resolution census data, detailed commuting patterns from over 40 countries, and global air travel data from more than 3,800 airports to realistically capture how infections move within and between populations. Users can define disease characteristics (e.g., incubation time, transmission rate) and run simulations to visualize and analyze outbreaks across time and geography. The GLEAM engine simulates the infection dynamics according to the characteristics of the disease coupled with any prevention and intervention measures. There is a public version (GleamViz), and a Pro version (GleamViz Pro), available by request, that removes limitations on simulation size and runtime for large-scale, expert-level research.