Opensilver

OpenSilver is an open-source framework for building web applications with C# and XAML, the languages and markup used by Microsoft WPF and Silverlight. Its tagline is WPF and Silverlight for the modern web: you write .NET code with familiar XAML layouts, and the result runs in browsers such as Chrome, Firefox and Safari, as well as on Windows, Android and Mac through hybrid hosting. The full stack is released under the MIT license.

What is new

Version 3.3 lets Blazor components run directly inside XAML applications, so teams can mix the Blazor ecosystem with XAML user interfaces. The release also adds .NET MAUI Hybrid integration and an AI-enhanced drag-and-drop UI designer, and the project emphasizes compatibility with existing WPF and Silverlight code. Developers can write in C#, Visual Basic or F#.

Key features

• C# and XAML web development with a WPF-compatible programming model.
• Support for enterprise libraries and patterns, including RIA Services and LightSwitch.
• Blazor components embedded in XAML apps.
• MAUI Hybrid integration for desktop and mobile packaging.
• An AI-assisted visual UI designer.
• XAML.io, an online .NET IDE that lets you try OpenSilver with no install or signup.
• A gallery of samples and controls.

Migrating legacy apps

A major use case is moving old Silverlight or WPF line-of-business applications to the browser. OpenSilver presents two options. The do-it-yourself route uses the open-source SDK, documentation and community support to port the code yourself. The second route is a migration service in which the OpenSilver team does the work, aiming for an application that looks and behaves like the original at a lower cost and in less time than a full rewrite. The site offers quotes and calls with an expert for that service.

Use cases

Enterprises with Silverlight applications that no longer run in modern browsers can bring them back without rewriting the business logic. .NET teams that prefer XAML over HTML and CSS can build new web apps with skills they already have. Developers evaluating the approach can experiment in XAML.io before installing anything.

Pricing

The framework and SDK are free and open source under MIT. Professional migration and support services are sold separately on a quote basis.

Who it is for

OpenSilver is aimed at .NET developers and organizations with WPF or Silverlight investments. It is less relevant for teams already committed to JavaScript frameworks, since its value lies in reusing C# and XAML code and knowledge.