Supply chain design, management and assessment are key success drivers in nowadays globalised economy. With the advent of new paradigms such as sustainability and mass customization, a new generation of tools is required. This work presents a supply chain simulation tool that allows to take into account the specificity of mass customized markets, efficiently dealing with the adjustable product physical structure and the complexity of handling customized Lot Size One orders. Moreover, this tool is integrated with a sustainable Assessment Engine that allows to configure, since the product design phase, the entire supply chain in a lifecycle perspective. In order to ensure a wide applicability of the tool, this is developed using a client-server architecture and exploiting a Shared Data Model that facilitates the integration of many applications coming from different providers thus giving a powerful decision support tool to companies’ decision makers.