OpenSilver 1.1 Released Offering 99% Silverlight Compatibility
Written by Kay Ewbank   
Friday, 21 October 2022

OpenSilver 1.1 has been released with improvements including over 100 new Silverlight features and three times faster performance compared to version 1.0. The open-source alternative to Silverlight is capable of running large, complex legacy applications, as well as newly written C# and XAML applications.

OpenSilver was first released in 2021 at the same time as Microsoft ceased support for Silverlight. Userware, the French software company that originated it as an open source project hosted on GitHub, created it because they felt developers should not be compelled to rewrite existing applications because of a change in the underlying stack.


OpenSilver uses Mono for WebAssembly and Microsoft Blazor to bring back the power of C#, XAML, and .NET to client-side Web development.

For those who have Silverlight apps, OpenSilver has advantages. It supports .NET Standard, .NET 5, and .NET 6, in addition to legacy Silverlight code. It uses features of the C# 9.0 and supports the latest Visual Studio. OpenSilver is also compatible with all JavaScript libraries, combining the best of both worlds.

The new version adds support for over 100 additional Silverlight APIs, meaning developers can now reuse more than 99% of their Silverlight application’s code. The new features include a new datagrid that is based on the original code from Microsoft. Most Silverlight controls are now supported in OpenSilver, including DataForm, Accordion, AutoCompleteBox, DataPager, and LineSeries.

The layout system has been improved and now supports the Measure and Arrange Silverlight APIs for creating custom panels and layouts. The new version also adds support for more third party libraries, including Telerik UI.

The developers day that new features including Virtualization, .NET 7 support, and several major optimizations have led to a "significant improvement of overall performance", in many cases by up to three times that seen under OpenSilver 1.0. The team says that VB.NET support in the browser is next on the agenda, making OpenSilver the only technology available that supports VB.NET and XAML to build web apps. VB.NET support is expected to come in OpenSilver 2.0, planned to be released early 2023.

OpenSilver 1.1 is available now. 


More Information

OpenSilver website

Source code on GitHub

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