In the past year, two rapid simulation tools for natural hazards were developed. Fastflood.org features a rapid simulation method for rainfall-runoff, routing and hydraulic modelling, averaging over 1500x faster than full simulation while achieving over 97 percent accuracy in simulated flooded areas. Fastrocks.org, a new addition to be published early 2024, provides a soil depth, slope stability and mass movement simulation tool with over 500 times speed increase over full debris flow models. Both of these tools are available as open, free, web-based simulation platforms, and are linked with global and satellite-based datasets to enable rapid assessment and interactive scenario-exploration. In this session we will organize a hands-on workshop with these tools. Using the automated data input tools, you can start exploring the workings of the model and the behaviour of the hazards in your own area. Best practices for improving your initial model using custom data or the built-in automated calibration tools will be explained. The limitations and opportunities of these simulation platforms will be explored to several study examples that can be simulated interactively during the workshop. In addition, the underlying technologies will be presented, both the numerical algorithms used to speed up the simulations, as well as the web-technologies used to host the platforms. Due to the usage of web-assembly, simulations run locally, and all user computations and data remain fully on the users device. Finally, the latest validation research will be highlighted.