Capella

Eclipse Capella is an open source model based systems engineering tool for designing the architecture of complex systems. It implements Arcadia, a structured method developed for systems architecture work, and the pairing of a specific method with a tool built to enforce it is what distinguishes Capella from general purpose modelling software.

Method and tool being designed together is the point. A general modelling tool will accept almost any diagram an engineer draws, which sounds like flexibility but in practice means every team invents its own conventions and models stop being comparable across a programme. Arcadia prescribes a sequence of analysis levels from operational need through system need to logical and physical architecture, and Capella guides engineers through those levels rather than leaving the approach open.

Being open source changes the adoption question substantially in this category, where commercial systems engineering tools carry high per seat licence costs. A team can trial the method properly, and a supply chain can standardise on one tool without every subcontractor buying licences, which is what makes shared models feasible across organisations.

An ecosystem of extensions supports a digital thread across engineering disciplines, connecting the architecture model to requirements, simulation and other downstream tooling. The project publishes short introductions to both the tool and the Arcadia method.