Upgrading to Mendix 11: How Maia and mxcli keep your documentation up to date

Ask any Mendix developer what they would rather do, build a new feature, or spend half a day documenting the last one, and you already know the answer. Documentation may be far less rewarding than coding, but that is not the only reason it slides to the bottom of the backlog.

Under tight deadlines and pressure to deliver working code, documentation is usually the first thing to go, and what does get written tends to be informal, hard to follow and quickly out of date. The messier the existing docs become, the less point developers see in adding to them, and the gap only grows with every release.

What if documentation could keep itself up to date, scaling with the application and traceable to every change? For many teams, it would change more than daily development. It would change how they look at upgrading to Mendix 11.

The hidden cost of undocumented Mendix apps

Many Mendix applications have been running in production for years, some since Mendix 6 or 7, and many of them are business-critical. Upgrading them to Mendix 11 should be an obvious step. Instead, it often feels like a step into the unknown.

When so much of what the app does lives in people's heads, nobody can say exactly what is in it, what will break, or how long it will take to find out, leaving teams faced with three dilemmas:

1. Upgrade now, or keep building on old ground?

Upgrading means facing what years of changes left behind: hidden workarounds, deprecated widgets and old modules nobody remembers. Each major Mendix version also retires older widgets, modules and Java versions, so an upgrade often means replacing parts of the app, not just recompiling it. But staying put means every new feature is built on a foundation that falls further behind, while Mendix 11 capabilities such as Maia stay out of reach.

2. Move fast, or keep it stable?

The business wants new features, more users and new integrations. Without documentation, though, nobody can predict the impact of a change, and without tests or a clear description of how each process should behave, nobody can confirm that everything still works afterwards. Every release becomes a trade-off between speed and stability, and scaling the app gets harder each time.

3. Invest in the upgrade, or in new features?

If you cannot scope an upgrade, you cannot estimate it. Every process has to be checked by hand, and the experienced developers who could answer the questions may have moved on. Faced with an unclear cost and a working app, budgets go to visible features instead. The upgrade keeps getting postponed, and every year it waits, it gets bigger and more expensive.

Take the guesswork out of your Mendix 11 upgrade

With Mendix 11, developers finally gain what legacy apps have been missing for years: a clear view of their application and the tools to change it with confidence.

1. Document your Mendix app before you change anything

The first step out of the unknown is a map. Maia, the AI assistant built into Studio Pro, and the Mendix CLI (mxcli), a command-line tool from Mendix Labs that lets coding agents such as Claude Code or Codex work with a Mendix project, can both inspect an application and expose its structure: modules, entities, microflows, pages and the dependencies between them.

An agent can turn that metadata into clear documentation of how the app works, without a developer having to reverse-engineer it by hand. mxcli adds linting and best-practice reports that flag issues and outdated patterns, making technical debt visible before the migration even starts.

2. Move fast without losing control

Once the app is documented, every change becomes easier to judge. mxcli's impact analysis shows which microflows, pages and entities a change will touch before anyone makes it. But more importantly, the documentation no longer falls behind.

After each change, whether a new page, a new attribute or new business logic, the agent updates the documentation as part of the same task, serving two audiences at the same time. Developers and business users read it to understand the app, and AI agents use it to guide the next change or to power an assistant that helps new users find their way.

Because Maia and mxcli work on the Mendix model rather than on thousands of lines of raw code, the output stays easy to review.

3. Turn your Mendix upgrade into an informed decision

When you can see what is in the app, you can scope the upgrade. When you can scope it, you can estimate it, and the budget discussion becomes a business decision instead of a leap of faith.

The platform you upgrade to matters too. With Mendix 11.12, the first Long-Term Support (LTS) release of Mendix 11, teams get a stable foundation for long-term maintainability, security and scalability, and the AI-assisted tooling that comes with it is ready for business-critical production apps. Maia Plan turns a description into epics and user stories, and Maia Make starts implementing them, so the investment keeps paying off long after the migration.

4. Lay the foundation for the agentic enterprise

An application that documents itself, is also ready for what comes next. This is exactly what companies get with Mendix in the context of enterprise orchestration.

As part of Siemens Intelligence Center X (ICX), Siemens' industrial AI orchestration software, Mendix, together with Maia and mxcli, plays an important role in making applications understandable to agents and people alike. With Mendix 11.12, an app can act as an MCP server that exposes its logic, data and workflows to other AI tools, and Mendix Workflows can orchestrate agents and people inside a governed, auditable trust layer, creating the foundation for the hybrid workforce that brings people and AI agents together.

See mxcli in action: one prompt, feature and documentation done

In a recent demo, Erick Souza, Sr. Mendix Developer & Mendix MVP at CLEVR, showed how a single prompt can build a new feature and update the documentation in the same run. No one has to sit down and write it afterwards. Here is what he showed, if you don't have time to watch the full video.

Could a developer make these changes by hand? Of course, but it would take longer. Here it happens automatically, every time.

Upgrade to Mendix 11 with confidence, starting with your documentation

Download mxcli from the Mendix Labs GitHub page, drop it into your project folder and run mxcli init. Within minutes, your project is ready for the coding agent of your choice, whether that is Claude Code, Codex or another tool.

From there, the first prompt is the most valuable one: ask the agent to document what is already in your app, then make updating the documentation part of every prompt, and your team's knowledge grows with the application instead of falling behind it. One word of caution: mxcli is still alpha software and evolving quickly, so always work on a copy of your project or under version control, and review the agent's changes the way you would review a colleague's work.

The result is a foundation you can build on. An application your team understands, an upgrade you can plan, and an architecture ready for the agentic enterprise.

Curious what this could look like for your applications? Contact CLEVR to request a demo.