DICE is the most commonly used integrated assessment model for studying the economics of climate change. It has been used in numerous publications and by the federal government to compute the social cost of carbon. webDICE will provide a web-based implementation of DICE allowing anyone to run the model. The goal is to allow citizens and policymakers to better understand the implications of choices they make about emissions. Users will be able to vary the assumptions underlying the model both by varying parameters and by choosing alternative modules such as alternative models of carbon cycle. They can then run DICE to see how their choices and assumptions affect the economy. The underlying DICE code, currently written in MatLab, is completely modular and freely downloadable, allowing users to modify it or use it themselves as desired. webDICE provides user-modifiable graphical output; it displays a set of default graphs and also allows users to plot any of the output data. It also allows users to download all generated data as a CSV file. webDICE will automatically generate Monte Carlo simulations for user-chosen parameters and allows optimization subject to user-chosen constraints, such as finding the optimal carbon tax subject to the constraint that temperatures not increase by a given amount.