The latest version of OpenSilver 3.2, a remake of Microsoft's retired Silverlight web application framework, extends the platform to mobile devices using a .NET MAUI Hybrid approach.
OpenSilver was launched in October 2021 by a French company, Userware. It is an open-source, MIT-licensed reimplementation of Silverlight. OpenSilver compiles .NET and XAML code into HTML5 and WebAssembly, reimplementing standard and selected third-party controls. It allows developers to reuse their legacy Silverlight or XAML applications instead of rewriting them. The latest update to OpenSilver was version 3.1 in December 2024, with a Visual Studio Code XAML designer and modern themes for the UI.
Until now, OpenSilver focused on WPF and Silverlight code parity on modern browsers. In version 3.2, there are new project templates featuring .NET MAUI hybrid applications. In these applications, there is a native app container for every platform that hosts the native WebView, which runs the OpenSilver application.
The benefits for the developers include maintaining a single codebase, with a consistent UI on all platforms. Native apps can use their platform APIs in the OpenSilver applications. Lastly, native apps are packaged and distributed on the app stores, making it easier for users to find them. The included ToDoCalendar sample application that illustrates how cross-platform OpenSilver works was ported from the app initially written for the defunct Windows Phone.
Right now, the supported platforms for .NET MAUI hybrid OpenSilver applications are iOS, Android, Windows, macOS, web browsers and Linux (using Photino, a native Linux framework using web technologies).
When asked how have developers received OpenSilver, Giovanni Albani, Userware founder and CEO answers:
The reception has been remarkably positive, particularly among enterprise development teams with significant WPF investments. We've seen adoption across finance, healthcare, and manufacturing sectors, where preserving complex business logic while expanding platform reach is essential. What resonates most with businesses is the cost-effectiveness of modernizing existing applications without rebuilding from scratch, while leveraging their teams' existing C# and XAML expertise. Microsoft's recommendation of WPF for new desktop application development has reinforced this interest. Interestingly, new generations of developers are discovering WPF through OpenSilver and finding its capabilities impressive. They appreciate that it's a stable, well-documented platform with abundant samples and tutorials.
Other features in this release include a couple of updates for WPF compatibility, such as improved event bubbling (matching behaviour present in WPF) and support for RTL languages. The company intends to further improve WPF code compatibility in future releases. Additionally, the XAML editor previously available for Visual Studio Code is now available for Visual Studio 2022.
According to Giovanni Albani, (the) XAML visual editor for VS Code generated particular excitement in the developer community, with its Reddit announcement garnering over 100,000 views and more than 120 comments.
The OpenSilver source code is available on GitHub. The repository containing OpenSilver has 1067 stars and has been forked 122 times. Beyond the Userware developer team, there are other active contributions to the project, with a total of 47 contributors. According to the OpenSilver website, companies that rely on this framework include Bayer, TATA, KPMG, and others.
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