The management of renewable and distributed energy resources is changing the way in which electric distribution systems are being operated. Many companies commonly create several custom system solutions to manage power distribution. The functions provided by these systems are network visualization, state estimation, system control and data acquisition, among others. Despite their relevance, many mid-size or small distribution companies have problems to install one of these solutions because they are either very expensive, incompatible, or limited by difficulties in data exchange. As a possible solution to this problem, this paper presents the development of a Distribution Management System (DMS) based on open source technology. This system combines four main components: OpenDSS-framework, ActiveMQ-broker, applications for visualizing and editing electrical network, and Common Information Model (CIM). The tool is part of Tenergia R&D project 1This work is financed by R&D projects FITS 2013 – UREE10 – FONARSEC – Ministry of Science, Technology and Productive Innovation of Argentina, and PIDDEF 36/14 – Ministry of Defense of Argentina.1 and has a collection of applications designed to monitor and control the distribution networks located in Argentina.