Wildfire simulators and decision support systems can assist the incident command teams in charge of tactical wildfire suppression. This paper presents a web-based wildfire simulator developed to provide real-time support for wildfire management. The paper describes the overall software architecture, the modelling chain characteristics and the results produced by the simulator considering a set of actual wildfires that occurred in the island of Sardinia, Italy. The simulator consists of a graphical user interface that deals with data input–output management, a mass-consistent model devoted to the downscaling of wind fields, and a module that provides a spatially explicit representation of wildfire propagation. The simulator is a client‐server application that is operated through a web-based graphical user interface that leaves the computational work to a dedicated server; most of the code is parallelised in order to minimise computational run-time. The validation phase demonstrated the capabilities of the simulator in providing wildfire predictions with a substantial agreement with actual wildfires, and a computational cost suitable for faster than real-time applications. The simulator is proposed as a tool to provide assistance to civil protection and fire management agencies during the incident response phase. The simulator is also appropriate for the training of personnel.