Userware adds WPF-to-web migration tools in XAML.io

Userware has released version 0.8 of XAML.io, adding new tools to help migrate Windows Presentation Foundation applications to the web. The update includes a free, browser-based migration workflow built on the OpenSilver framework.

The new feature, Migrate from WPF, lets developers analyse a compiled WPF application for web compatibility, import a project into the browser and run it there, or request a managed migration from Userware.

The launch addresses a long-standing problem for organisations with established desktop software estates. Many businesses still rely on internal applications built in WPF, a Microsoft framework widely used for Windows desktop software, but face pressure to make those applications accessible through browsers without rebuilding them from scratch.

Userware says its approach preserves the original C# and XAML code instead of relying on AI-generated rewrites or moving teams to a different user interface model. Developers can review automatic changes, with unsupported C# wrapped in compiler directives and unsupported XAML flagged with comments.

A compatibility analyser sits at the front of the workflow. It reads a compiled application, identifies the WPF and platform APIs in use, and generates a report showing which features already run on OpenSilver, which need adaptation, and which remain blockers.

According to Userware, binaries are processed locally in the browser, and only an aggregated list of unsupported features is sent to its servers to generate the report. The full migration flow can also run in the browser without sign-up, while cloud save, sharing, and AI tools remain optional.

After analysis, developers can import source code into XAML.io and run the application in a browser. On import, the tool applies a WPF-style theme so the web version resembles the desktop original, though teams can later switch to a more modern theme and add responsive layouts.

Reference app

To demonstrate the migration path, Userware migrated Family.Show, a reference WPF application originally built by Vertigo for Microsoft. It says 97% of the original code remained unchanged, based on a line-by-line comparison of the C# and XAML files in the original and migrated versions.

Family.Show is more complex than a basic sample application, with custom controls, animations, data templates, drag-and-drop functions, and photo handling. Userware has made the migrated version available in the browser alongside the source code, allowing developers to compare the two codebases directly.

According to Userware, the migrated Family.Show application, including the .NET runtime, is 8.1 MB when compressed. No browser plug-in is required because OpenSilver runs on WebAssembly and renders XAML as HTML DOM elements.

That design distinguishes OpenSilver from earlier browser efforts tied to plug-ins and places the interface inside standard web structures rather than a canvas layer. Userware argues that this gives migrated applications a stronger base for browser search, web integration, and accessibility standards including Section 508 and EN 301 549.

Migration limits

Userware has also been explicit about the current boundaries of the release. It says the compatibility analyser is ready for applications of any size, but the in-browser source import remains a technology preview and is best suited to small and mid-sized self-contained projects.

Larger applications still require some manual work, and third-party UI control suites are not yet supported in the self-serve tools. Those cases are handled through managed migration work with Userware's services team.

The underlying compatibility layer currently includes eight Roslyn analysers and 16 automatic code fixes. Coverage of WPF features is still expanding, Userware says.

OpenSilver itself has been under development since 2013, initially in the CSHTML5 project before being refocused on WPF support. Userware presents XAML.io version 0.8 as a migration layer built on that existing framework rather than as a new framework launch.

Commercial model

The migration tools are free to use, while OpenSilver is open source under the MIT licence. Userware says it funds the free tooling through optional professional services and customer sponsorship of specific WPF features, which are then added back to the open-source framework.

Developers can export a standard Visual Studio solution at any point and continue work in other environments such as Visual Studio, VS Code, or Rider. Userware says that is intended to avoid lock-in to the browser-based tool.

Userware also used the launch to underline a broader argument against rewriting established desktop software for the web in a different stack. It positions the product as a way to preserve working code and reduce behaviour drift during migration.

A quote provided with the launch set out that position. "WPF isn't going anywhere on the desktop. But a lot of these apps now need to live on the web too, and getting them there shouldn't require a rewrite," said Giovanni Albani, Chief Executive Officer, Userware.