The latest version of OpenSilver 3.0, a remake of Microsoft's retired Silverlight web application framework, introduces a new drag-and-drop user interface designer with AI code generation. It also brings OpenSilver to VS Code and non-Windows platforms.
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 2.2 in April 2024, with the support for LightSwitch application migration.
The most important feature in the new version is the UI designer. Previous versions of OpenSilver didn’t have a WYSIWYG UI designer and were limited to the markup editor and UI preview. Now, the UI designer is interactive and works in Visual Studio, as the original Silverlight UI designer used to do.
The new UI designer for OpenSilver, in Visual Studio
The designer has integrated AI support for creating and changing the UI. The AI can understand textual commands like "add a navigation menu at the top, change the style to a red theme and make the text black". AI commands can also be done on individual elements of the UI. At the moment, the AI support in the designer is still in preview.
Concurrently with the new update, Userware launched an online version of the UI designer, at XAML.io. The online designer is made in OpenSilver and allows the users to transition the UI designed in the browser to Visual Studio exporting a ZIP file with the source code.
OpenSilver 3.0 supports development in multiple languages, including C#, XAML, F#, and VB.NET. It allows developers to target all major platforms, including web browsers (Chrome, Firefox, Safari, Edge), desktop operating systems (Windows, macOS, Linux), and mobile devices (iOS, Android), from a single codebase. With this release, support for Visual Studio Code has been added, extending the development environment to Windows, Mac, and Linux systems, and simplifying the development process across different environments.
Even if OpenSilver is specifically targeted to migrate Silverlight applications, according to Vasil Buraliev from Userware, it also has decent WPF compatibility:
Currently, 70% to 80% of a WPF application code can be reused ‘as-is’ in OpenSilver 3.0, and we are still working on expanding the coverage.
Userware plans to expand the capabilities of OpenSilver with several upcoming features: .NET MAUI Hybrid Support, Blazor Components in XAML, XAML 3D for creating 3D websites and Mixed Reality experiences and Rider editor support. These are the most-demanded feature requests from the users, according to Vasil Buraliev.
The company admits that it’s difficult to put numbers on the exact adoption of OpenSilver. The SDK has been downloaded by more than 12.000 people. A few thousand businesses of all sizes
have contacted Userware for migration support or advice, while the company has done several dozen big migrations, with more than million lines of code
which are running in production behind firewalls, says Mr Buraliev.
The OpenSilver source code is available on GitHub. The repository containing OpenSilver has 935 stars and has been forked 115 times. Beyond the Userware developer team, there are other active contributions to the project, with a total of 48 contributors. According to the OpenSilver website, companies that rely on this framework include Bayer, TATA, KPMG, and others.