A open-source reimplementation of Silverlight has been released. OpenSilver is a modern, plugin-free, open-source version of Microsoft’s Silverlight solution that runs on current browsers via WebAssembly. 

The team explained that while Microsoft Silverlight has enabled developers to build rich Internet apps using C#, XAML, and .NET, browsers have stopped supporting plugins. As a result, many Silverlight applications no longer work. In addition, Microsoft is thinking about ending support for Silverlight after 2021. OpenSilver is meant to bring C#, XAML and .NET back to client-side web development. 

The project can be used to create new applications or modernize existing Silverlight applications. The apps created with OpenSilver will be compatible on browsers that support WebAssembly, which currently includes major browsers and  platforms like Edge, Chrome, Safari, Windows, macOS, iOS, Android, Linux and ChromeOS.

“When an application is compiled using OpenSilver, it runs on all those browsers without requiring users to install a plugin,” the team wrote in a post. “Existing Silverlight applications need to be recompiled with OpenSilver in order to run on those browsers.”

OpenSilver is currently in a technology preview, which covers about 60% of the Silverlight API. The team is currently working on supporting Open RIA Services and Telerik UI for Silverlight. It will also be updated in sync with Blazor and Mono for Web Assembly