It's been 15 years since Axon Framework 1.0 was released. Fifteen years of production systems. Fifteen years of mission-critical applications. Fifteen years of helping teams build software that actually deals with the complexity of their domain instead of drowning in it.

That's not a small thing. A 15-year-old open source framework isn't a pet project. It's not some side hustle. It's battle-tested, production-hardened infrastructure that enterprises trust with their most critical systems.

It's also been 15 years of significant investment. Investment in time, in talent, in infrastructure. And that investment is only getting more expensive as thousands of companies leverage it, including 80% of the Fortune 100. AI-assisted development tools don't maintain themselves. Cloud infrastructure doesn't run on good intentions. Security patches don't write themselves at 2 AM.

We founded Axoniq specifically to back the development of Axon Framework. To make it sustainable. To ensure it could keep evolving, keep improving, keep serving the community, from an individual developer with a ground-breaking idea, to the enterprise delivering services we all depend on. The gap between how much value the framework creates and how much of that value flows back to fund its development has always been the hard problem of open source. The framework has enabled countless teams to build maintainable, scalable, event-driven systems. It's helped organizations navigate complexity that would have sunk their projects otherwise. But making that economically sustainable has been an ongoing challenge.

The sustainability challenge

Open source has an inherent tension that every project at this scale eventually faces: the organizations extracting the most value aren't always positioned to contribute back proportionally.

We see vibrant participation from individual developers and smaller companies. They file issues, submit pull requests, help with documentation, and participate in forums. Larger organizations engage differently. They build critical systems on the framework, integrate it deeply into their infrastructure, and depend on it for production workloads. The nature of how they engage with the community is simply different and that creates a gap between the value the ecosystem generates and what flows back to sustain it.

This isn't unique to Axoniq. It's a fundamental challenge of open source at enterprise scale. And it's a challenge we have a responsibility to solve.

We need a model that creates the right incentives for everyone. One where organizations benefiting most from advanced capabilities contribute to the cost of building and maintaining them. One where the core remains free and accessible to every developer who wants to build on it.

So we're being pragmatic about sustainability.

What we could have done (but didn't)

Over the past few years, we've watched several prominent open source projects change their licenses. They moved from permissive open source licenses to restrictive "source-available" licenses like BSL or SSPL.

Their reasoning was similar to ours: cloud providers and enterprises were benefiting massively from their work without contributing back. The sustainability challenge was real.

We could have followed that path. It would have been the "logical" solution. Relicense Axon Framework under BSL or a custom commercial license. Force everyone to pay or fork.

That's not who we are. We truly believe in the power of open source. Not just as a distribution model, but as a way of building software that's better, more transparent, and more trustworthy. That belief isn't negotiable.

What we're actually doing

Axon Framework is staying open source. Full stop. Apache 2.0, just like it's always been. The code at org.axonframework will remain freely available, forever.

But we're introducing something new: Axoniq Framework. Those two letters - "iq" - make all the difference.

Let me be clear about what's happening. As we release Axon Framework 5.1 and introduce Axoniq Framework by the end of April, we're consolidating our commercial offerings. Some features from 4.x, like the Dead-Letter Queue and Distributed Tracing, are moving to the commercial version. Other features, like distributed message buses, were already announced as commercial extensions last year. They'll now be part of Axoniq Framework. And we're adding new production-grade capabilities like DCB, Workflows and Durable Execution. Together, this is what enterprises need to run mission-critical systems at scale.

Axoniq Framework is the enterprise-ready version. It's true open core. Same foundation, same principles, same community, but with production-grade features for scalability, resilience, and operational excellence. The features that let you sleep at night when your event-driven system is handling Black Friday traffic, processing financial transactions, or managing healthcare data. Migrating between Axon Framework and Axoniq Framework is a matter of changing a dependency. The code is 100% cross-compatible.

Axoniq Framework will be published under io.axoniq.framework and will use a commercial, source-available license. You'll be able to see the code. You'll be able to inspect it, audit it, and understand how it works. But if you want to use it in production, you'll need a license.

This isn't about locking anyone out. The pricing model will be accessible to small companies. We're not building this for Fortune 500s only. If you're a startup with three developers building something amazing, we want you to have access to these features too.

The core framework isn't getting feature-starved. Axon Framework 5.x will continue to be a fully functional, production-capable framework. It's what it's been for 15 years: solid infrastructure for event-driven systems.

Axoniq Framework just takes it further for organizations that need that extra mile.

But as we evolve the framework, we're making a deliberate choice about where to invest our development effort. The enterprise features that require significant ongoing maintenance and support are moving to the commercial version. The core framework remains open source and production-capable. It's an open core model: respecting the community while enabling sustainable development. Stay on 4.x, upgrade to 5.x open source, or add Axoniq Framework for enterprise features. Choose what works best for you.

What happens next

As we move forward with 5.x, active development and public maintenance of 4.x will conclude. This means no new public patches or bugfixes for the 4.x line. The code remains open source and available, but our development focus shifts to 5.x. Commercial support customers will continue to receive maintenance and updates for 4.x through private channels for an extended period.

As for the rollout of Axoniq Framework, here's what to expect. Over the coming months, you'll see Axoniq Framework emerge. We'll be transparent about what's in the commercial version, what stays in the open source version, and how to switch between them.

What this means for you

Part of the reason we're making this transition is specifically to be able to offer more to the community. Not less. Organizations with under 10 employees and under $10M in revenue get access to Axoniq Framework on the Team plan at no charge. We want every developer building something ambitious to have access to these capabilities, not just the enterprises.

Individual developers can use Axoniq Framework for free on the Dev plan. For organizations running Axon Framework at scale, Axoniq Framework provides a clear path to access enterprise features while supporting continued development.

And for the companies that have been contributing, participating, and supporting the community all along?

Thank you.

You've kept this project alive. You've proven that open source can work when everyone does their part. We haven't forgotten that, and as we work out the details of how this transition works, we're thinking carefully about how to recognize those contributions.

The future is still open

I started this journey 15 years ago because I was fed up with software that was more complex than the problems it solved. That mission hasn't changed. If anything, with AI fueling the 5th wave of computing, that mission has only become more urgent.

Event sourcing, CQRS, and event-driven architecture are powerful tools for managing complexity. But they need solid infrastructure to work well. That's what Axon Framework provides. That's what Axoniq Framework will enhance.

The code at the heart of all this stays open. We're still committed to the community. The mission stays the same.

We're just adding a sustainable business model around it. One that respects both the open source community and the reality of running a business that maintains production infrastructure.

We've made the last fifteen years count. We're committed to making the next fifteen even better.