Distribution System Interaction Model Analysis - A testbed for the quantitative analysis of interaction models within distribution networks.DSIMA is an open-source testbed to simulate interaction models governing the exchange of flexibility services located within a distribution network. The testbed is an agent-based system in which the distribution system operator, the transmission system operator, producers and retailers takes their decisions based on mixed-integer linear programs. This testbed helps to highlight the characteristics of an interaction model, its benefits for the agents and ease the detection of unwanted or abuse behaviors which decreases the welfare. The testbed is implemented in Python and the optimization problem are encoded in the modeling language ZIMPL. A web interface is coupled with an instance generator using macroscopic parameters of the system such as the total power production. This tested is therefore well suited to test the implemented interaction models on various scenarios and extend the implementation to other models.