Capella is an open-source and field-proven Model-Based Systems Engineering (MBSE) solution to successfully design systems architecture. It provides systems, software and hardware architects with rich methodological guidance relying on Arcadia, a comprehensive model-based engineering method based on both industrial experimentations and system engineers' feedback : better understand the customer need, define and share the solution, secure SW/HW engineering and subcontracting, early evaluate and justify architectural choices, prepare and master V&V.