Capella is an open-source Model-Based Systems Engineering (MBSE), initially developed and deployed by Thales in 2010 and now largely used in many domains worldwide.

The Capella tool embeds a method named Arcadia, promoting a comprehensive and pragmatic MBSE approach. As a free and open-source tool, Capella is a very efficient and low-cost solution for both small and large critical Systems Engineering projects, enabling Systems Engineers to embrace the MBSE cultural change.