Nowadays we face an age of massive Internet usage. With Online Social Networks (OSN) we practically live this parallel reality where everything we do and everyone we met is exposed and shared through these online "worlds". Today, being able to study and understand how information flows and how relationships are built within these online networks is of paramount importance for various reasons, social, educational, political or economical. That is why social networks analysis has become an important scientific and technological challenge. In this paper, we propose the Socii system for social networks analysis and visualization. Socii aims at helping OSNs users to exploit and understand their own networks through a user friendly interface. The system relies in four main principles, namely simplicity, accessibility, OSNs integration and contextual analysis. Socii's architecture and implementation technological choices are presented, together with its main functionalities