The Decision Deck project aims at collaboratively developing open source software tools implementing Multiple Criteria Decision Aid (MCDA). Its purpose is to provide effective tools for three types of users: - practitioners who use MCDA tools to support actual decision makers involved in real world decision problems; - teachers who present MCDA methods in courses, for didactic purposes; - researchers who want to test and compare methods or to develop new ones. In this talk, we present the Decision Deck project and detail the different research initiatives which have emerged inside it. In particular, we focus on the diviz software platform which is a tool for designing, executing and deploying MCDA methods.