Userware has released version 0.7 of XAML.io, adding browser-based publishing for native desktop applications on Windows, macOS and Linux. The update brings desktop packaging to the company's free web-based .NET IDE.
The new feature lets developers compile a C# and XAML project in the browser and download it as a Windows .exe, a macOS .app bundle or a Linux executable. The packaging process runs locally in WebAssembly and does not send source code to a server.
XAML.io already offered tools for writing, compiling and previewing .NET applications in the browser, using the same XAML designer as OpenSilver. With this release, it expands from browser-based development into desktop distribution, producing native .NET 10 processes rather than browser windows wrapped in a desktop shell.
The browser downloads shared runtime and launcher components, while the application itself is assembled inside the browser tab. This is designed to keep the user's code on their own machine throughout the process.
Local packaging
The release includes macOS ad-hoc code signing carried out client-side in WebAssembly. That is notable because code signing for macOS applications is usually associated with Apple tooling running on Mac hardware, but Userware said the process can now be completed from within the browser.
Giovanni Albani, Chief Executive Officer of Userware, said the company had focused on proving the approach would work across environments.
"Signing a macOS app from inside a browser tab on a Windows PC sounds like it shouldn't work, and honestly we weren't sure it would until we saw it run. There is no build server in the loop. Everything happens on the developer's own machine, in WebAssembly, so the source code never leaves it. That combination of native output and full privacy is what we're most proud of in this release," Albani said.
The feature is currently in preview. Applications created through XAML.io are not yet signed with publisher identities such as Apple Developer ID or Windows Authenticode, so users will still face standard first-launch warnings from macOS Gatekeeper and Windows SmartScreen.
Each download includes a short README file explaining how to launch the application. Support for user-supplied code-signing certificates is planned.
Platform limits
The current version supports Apple Silicon on macOS and x86_64 on Linux. The applications are built on .NET 10 and are intended to run as native desktop processes.
Additional technical details indicate that the user interface is rendered through the operating system's built-in web view using Photino, rather than through Electron or a browser runtime. The published applications are also self-contained, single-file downloads compressed to roughly 30 MB to 40 MB for each operating system.
The release reflects broader interest in moving more software development work into the browser while retaining local packaging and execution. For developers working with .NET desktop applications, setup can involve operating system-specific toolchains and signing steps, especially when publishing across multiple platforms.
Darshin Vyas, Vice President of Sales at Userware, said the company wanted to reduce that setup burden.
"Most teams expect to spend the better part of a day wiring up toolchains before they can ship a desktop build. We wanted that to be a few seconds in a browser, with nothing to install and no account to create. Lowering that barrier is exactly what puts .NET in front of a lot more developers," Vyas said.
XAML.io remains free to use, with no sign-up required unless users want to save projects to the cloud or use its artificial intelligence features. Userware, based in Paris, is also behind OpenSilver, the open-source framework used to run C# and XAML in the browser through WebAssembly.