Userware launches XAML.io v0.9 for prompt-built .NET apps

Userware has launched XAML.io v0.9, adding browser-based creation of .NET applications from text prompts. The release extends the company's XAML.io development environment with an AI agent that generates C# and XAML projects.

The new version is aimed at developers who want to start an application by describing it in natural language instead of setting up a project manually. The agent works directly on project files, compiles the application, reads errors, and iterates on the code when needed, according to Userware.

For its launch demonstration, Userware gave the system a single instruction to build a version of Paint as it appeared in Windows 98. The agent then worked for 42 minutes and produced about 3,500 lines of C# and XAML without follow-up prompts or manual edits, the company said.

The product focuses on .NET projects rather than the JavaScript-based web applications produced by many AI coding tools. Once an application has been generated, users can continue changing it through further prompts, direct code editing, or a visual designer in the same environment.

Projects created in XAML.io can also be downloaded as standard .NET 10 solutions. Developers can then move the work into Visual Studio and continue with existing .NET tools and workflows, rather than treating the generated application as a separate prototype.

The same project can be published to the web or targeted to desktop environments including Windows, macOS, and Linux, according to Userware. The release builds on features already present in XAML.io, including C# and XAML editing, visual design, NuGet package management, and .NET compilation to WebAssembly in the browser.

Giovanni Albani, Chief Executive Officer of Userware, said the company sees prompt-based software creation as a new entry point for .NET development.

"AI app builders have shown that people want to begin with an idea, not a toolchain," said Giovanni Albani, Chief Executive Officer of Userware. "Our bet is that .NET should be part of that future. We want to make the starting point radically simpler while keeping C#, XAML, and the .NET ecosystem underneath as the application grows."

Workflow choices

Userware is positioning the release around a mixed workflow rather than AI-only development. After the first generated version of an application, users can switch between prompt-driven changes, source code edits, and visual design tools on the same project.

"We don't think the future of software development is asking an AI to move a button five pixels," Albani said. "AI is extremely good at translating intent into larger changes. Visual tools are often better for precise ones. Source code gives developers full control. XAML.io lets users move freely between all three."

XAML.io v0.9 currently focuses mainly on application front ends, although generated applications can connect to external APIs and services, according to Userware. That places the tool in a part of the AI coding market where front-end generation is often the first point of adoption, while more integrated back-end support remains a separate step.

Migration work

The release also adds AI support for existing Windows Presentation Foundation applications. XAML.io already includes tooling to migrate WPF applications to the web, and the new agent is intended to handle migration cases that predefined transformations cannot resolve automatically, Userware said.

As a public example, the company highlighted its migration of Family.Show, a WPF reference application originally released by Microsoft. Userware said the web version retains 97% of the original C# and XAML.

Userware linked that migration feature to its longer history with XAML-based software. Its engineers have migrated more than 10 million lines of production front-end C# and XAML code over more than 13 years of customer projects, and that experience helped shape the new tooling, according to the company.

Pricing model

XAML.io itself remains free to use for source editing, visual design, package management, compilation, and execution without an account, according to Userware. Free accounts add cloud saving, sharing, hosted web publishing, and access to AI features.

Free users receive up to USD $5 of AI usage per month and can choose from several models, while the Pro tier costs USD $20 per month and includes USD $20 of AI usage with access to additional models, Userware said. Users can also see token usage and the dollar cost of each prompt, and track how much of their AI budget has been used.

Userware said customer code is not used to train AI models. XAML.io v0.9 remains part of the product's preview series.

Userware is the company behind OpenSilver, an open-source framework for running WPF-style C# and XAML applications in the browser under the MIT Licence.