OpenSilver - 2026 Pricing, Features, Reviews & Alternatives

OpenSilver is an open-source UI framework licensed under MIT that compiles C#, VB.NET, or F# and XAML into browser-compatible output using WebAssembly, HTML5, and CSS3. It targets enterprises and development teams maintaining legacy Microsoft Silverlight or WPF applications who need a path to the modern web without a full rewrite, as well as .NET developers building new line-of-business (LOB) and rich internet applications (RIA). Applications run in Chrome, Edge, Firefox, and Safari without browser plugins, and can be deployed to cloud services (including Azure), IIS, static file hosting such as GitHub Pages, or packaged as executables for the Apple App Store and Google Play via .NET MAUI Hybrid.

The framework ships with a drag-and-drop XAML UI designer featuring over 100 built-in controls, live design-time preview, and a real-time XAML designer for VS Code. An online IDE at XAML.io requires no installation or signup. Supported controls include the Silverlight Toolkit suite (DataForm, Accordion, AutoCompleteBox, DataPager, LineSeries, and others), a pixel-perfect backward-compatible DataGrid, Telerik UI for Silverlight controls, and LightSwitch support. RIA Services and Open RIA Services integration is included, alongside a Business Application project template for LOB apps. A modern UI theme with 12 customizable options covers light and dark modes inspired by Material and Fluent Design. Ahead-of-Time (AOT) compilation and a simulator with memory profiling and an Immediate window are available for performance and debugging workflows. An AI-enhanced designer (Preview) accepts natural language commands and image or mockup uploads to generate and modify XAML UIs automatically.

OpenSilver integrates with Blazor, React, and Angular, and Blazor Components run directly inside XAML applications as of v3.3. A single codebase targets web, mobile (iOS, Android), and desktop (Windows, macOS, Linux) via .NET MAUI Hybrid. XAP file upload enables automated migration analysis and workload estimation. Professional migration services and paid support packages are available from the vendor. The full source code is hosted on GitHub. Industries served include healthcare technology, transit and transportation, management consulting, commercial project management, and enterprise line-of-business software.