For more than a decade, the MBSE Capella tool and the Arcadia method have helped systems engineers address the complexity of designing large and critical systems. Today, the systems engineering landscape is entering a new phase, shaped by two major evolutions: the emergence of SysML v2 and the growing adoption of web-based engineering environments.
At Obeo, we believe that the principles that made Capella and Arcadia successful remain highly relevant in this new landscape.
This is why we are launching Capella for SysON, a new open source initiative within the Capella project that explores and progressively builds the convergence of Capella, Arcadia, SysML v2 and web-based modeling.
Our long-term ambition is for Capella for SysON to become the next generation of Capella.
What is Capella for SysON?
Capella for SysON brings the Arcadia approach to the SysON modeling environment.
SysON is an open source, web-based graphical modeling environment designed from the ground up for SysML v2 with a key differentiator: its flexible-by-design approach makes it possible to customize the workbench for different engineering methods. Capella for SysON extends this foundation with capabilities dedicated to Arcadia.
At its core, the project relies on a SysML v2 library for Arcadia, extending SysML v2 concepts, so that systems can be modeled according to the Arcadia method.
Part of the SysML v2 library that formalizes the core concepts of Arcadia
This library enables users to specialize SysML v2 models with Arcadia concepts.
A SysML v2 diagram containing elements specialized using the Arcadia library
As a result, models remain natively expressed using SysML v2 concepts and standard extension mechanisms, allowing them to participate in the broader SysML v2 ecosystem.
On top of this semantic foundation, Capella for SysON introduces Arcadia-specific graphical representations inspired by Capella. The objective is to let engineers manipulate SysML v2 model elements through graphical representations inspired by the concepts and modeling experience they already know from Capella.
A Capella for SysON diagram representing SysML v2 elements specialized with the Arcadia library
This combination opens an important perspective: using the standard language and ecosystem of SysML v2 while retaining the methodological guidance and engineering approach provided by Arcadia, helping teams get started more easily and scale their modeling practices for large and complex projects.
Preparing the next generation of Capella
Our long-term ambition goes beyond providing an Arcadia extension for SysON.
We intend Capella for SysON to progressively become the next generation of Capella, combining the foundations of SysON with the principles, methodology and key capabilities that Capella users rely on today.
This transition will take time. Capella is a mature engineering environment used on complex and long-running projects, with hundreds of wizards, helpers and model transformations designed to make the daily work of system engineers as effective as possible.
Building its next generation requires much more than reproducing diagrams in a browser. It means progressively bringing the concepts, workflows and capabilities that make Capella valuable to a new technological foundation.
Our objective is therefore not to replace today's Capella overnight.
It is to build a credible and progressive path toward a Capella environment that is:
- web-based, making deployment and collaboration easier in modern engineering organizations;
- compatible with SysML v2, connecting Arcadia-based engineering with the emerging standard and its ecosystem;
- built for collaboration, leveraging SysON’s architecture and capabilities, including standard REST APIs and textual syntax support;
- grounded in Arcadia, preserving the methodological approach that is central to Capella.
What does this mean for current Capella users?
If you are using Capella today, keep using Capella.
The current Capella platform remains the mature solution for operational Arcadia projects. Capella for SysON is still at an early stage and is not intended to replace it for operational projects today.
At the same time, we know that adopting a modeling approach is a long-term investment.
System architectures can live for years or even decades. Organizations invest significantly in their models, methods, tooling, training and engineering practices. The emergence of SysML v2 and web-based tools naturally raises questions about the future of these investments.
Capella for SysON is our answer to that question.
Our goal is to provide a progressive path forward, so that organizations using Capella and Arcadia today can benefit from web-based modeling and SysML v2 without abandoning the engineering approach they have built around Capella.
We envision this path in two steps.
First, we plan to enable existing Capella models to be exposed in SysML v2, allowing teams to continue working with Capella Desktop while making their models available to the broader SysML v2 ecosystem.
This will open the door to interoperability with SysML v2-compatible simulation and validation tools, as well as other SysML v2 modeling environments.
Then, as Capella for SysON matures, we plan to provide a migration path for existing Capella projects, enabling teams to move their models to the new environment and work directly with this new tool.
In other words, we are not asking the Capella community to choose between its existing investment and the emerging SysML v2 ecosystem.
We are working to connect the two.
Combining SysML v2 with a proven engineering method
Capella for SysON is also an important step for SysON.
SysML v2 provides a modern language for systems modeling, with a strong semantic foundation and a standardized way to describe systems.
But a modeling language alone does not define how an engineering organization should structure its systems engineering activities.
This is where Arcadia brings another dimension.
Arcadia provides a structured engineering method for reasoning about operational needs, system capabilities, functions, components and architectures. It has been developed and refined through years of industrial use.
By bringing Arcadia concepts to SysML v2, Capella for SysON aims to offer systems engineers more than SysML v2 modeling alone. It acts as a methodological layer that hides much of the underlying language complexity and guides users through their engineering activities. Instead of exposing dozens of possible concepts at any given time, each editor provides a focused set of tools relevant to the current activity.
For example, when working on operational needs, engineers focus on concepts such as Operational Actors and Operational Entities, without being exposed to concepts related to the physical architecture. By breaking down a complex engineering problem into focused modeling activities, Arcadia makes the modeling experience easier to learn, more efficient, and better suited to large-scale systems engineering.
The objective is to combine an emerging industry standard with a proven engineering method, and its associated graphical modeling experience, inspired by Capella, together with a flexible, low-code environment that can be tailored to each organization’s specific needs and engineering practices.
We believe this combination can become a compelling option for organizations looking at SysML v2 not only as a new modeling language, but as the foundation for their future MBSE practices.
SysML v2 gives engineers a powerful standard language. Arcadia provides a structured way to use modeling to reason about the architecture of complex systems.
A progressive roadmap
This journey has already started.
In 2025 and Q1 2026, in collaboration with Thales, the original creator of Arcadia and Capella, we have been laying the open source foundations for the convergence of Capella, Arcadia and SysML v2 through three complementary initiatives:
- Arcadia SysML v2 Library formalizes the core concepts of the Arcadia methodology using SysML v2 and KerML foundations. It provides the semantic foundation for using Arcadia in SysML v2 environments.
- Capella SysML v2 Bridge provides transformation capabilities from Capella to SysML v2, enabling existing Capella models to be exposed in SysML v2 while teams continue working with Capella Desktop. This paves the way for interoperability with the broader SysML v2 ecosystem.
- Capella for SysON brings these foundations into SysON, with the first Arcadia-specific modeling capabilities and Capella-inspired graphical representations in a web-based SysML v2 environment.
All three components are developed as open source projects, providing the building blocks for the future convergence of Capella and SysON.
In parallel, Obeo Enterprise for SysON is bringing the enterprise capabilities required to progressively deploy SysON in industrial contexts, with capabilities around collaboration, supervision and AI. These capabilities will also provide the enterprise foundation for future industrial deployments of Capella for SysON.
Together, these developments establish both the open source modeling foundations and the enterprise capabilities needed to bring this vision to industrial projects.
In 2027, our objective is to deliver a first Minimum Viable Product (MVP) of Capella for SysON. This MVP will bring these building blocks together into a coherent environment that organizations can start evaluating on concrete Arcadia use cases and use to provide feedback on the direction of the project.
Beyond 2027, our ambition is to progressively extend this MVP to cover the full scope of Arcadia and the key capabilities that Capella users rely on, while continuing to improve interoperability and the migration path from existing Capella projects.
This roadmap represents our current direction. Its pace and priorities will evolve based on technical progress, feedback from the community, and the involvement of industrial organizations willing to contribute to the initiative.
Building this future together
There is still significant work ahead. We are investing in this direction, and we also want to build this future through Open Innovation, together with industrial organizations that see value in bringing Arcadia and Capella into the SysML v2 and web era.
If this direction resonates with your own MBSE strategy, we invite you to join the initiative.
Talk to us about your needs, your use cases and your vision for the future of systems engineering. Experiment with the project and provide feedback. And if Capella for SysON is strategic for your organization, you can go one step further by co-funding parts of its development.
Organizations for which Capella for SysON is strategic can engage more deeply by contributing use cases, participating in the discussion around priorities and, where relevant, co-funding specific developments.
By engaging with the project, industrial partners can help shape priorities through concrete requirements and real-world validation, helping ensure that Capella for SysON addresses actual engineering needs and deployment constraints.
The involvement of early adopters will help us validate our choices, refine the roadmap and accelerate the transition from vision to an operational solution.
For current Capella users, Capella for SysON is about continuity and evolution.
And for teams exploring SysML v2, it is about combining a new standard with Arcadia, a proven model-based systems engineering method.
The future we are working toward is not Capella or SysML v2. It is Capella with SysML v2, powered by a modern web-based modeling platform.
Interested in being part of it? Contact us to discuss your needs, share your vision, and explore how your organization can contribute to Capella for SysON.
