Microsoft released .NET 11 Preview 1 yesterday, marking the start of the development cycle for the next major version of the framework. As with most first previews, the focus is on foundational improvements rather than large feature shifts, and the updates span libraries, runtime performance, tooling, and language support.
The library changes set the tone for the release. Zstandard compression support arrives as a modern option for faster and more efficient data handling, while a new BFloat16 floating‑point type targets machine learning scenarios that benefit from reduced precision. Text and file APIs see practical refinements through expanded Rune support, updates to ZipArchiveEntry, and the introduction of MediaTypeMap for MIME lookups. Security and systems work also move forward with new HMAC and KMAC verification APIs, hard link creation APIs, and additional integer division rounding modes. Networking reliability improves as well through Happy Eyeballs support in Socket.ConnectAsync.
These updates lead naturally into the runtime work, which continues Microsoft’s long‑term push toward performance and broader platform reach. Preview 1 expands Async CoreCLR support on WebAssembly, extends interpreter capabilities, and introduces new JIT optimizations. A GC heap hard limit is now available for 32‑bit processes. Meanwhile, ongoing work on RISC‑V and IBM s390x keeps the platform aligned with a wider range of hardware architectures.
Tooling improvements build on that foundation. The .NET SDK now supports interactive target framework and device selection for dotnet run, adds positional arguments to dotnet test, and offers new configuration options for dotnet watch. Additional analyzers and MSBuild performance updates round out the developer‑experience enhancements.
Language updates follow a similar pattern of incremental refinement. C# receives adjustments to collection expression arguments and layout support. F# sees more substantial changes, including parallel compilation by default, faster handling of computation‑expression‑heavy code, and new compiler flags. Visual Basic remains unchanged in this preview.
The web stack evolves alongside the languages. ASP.NET Core introduces an EnvironmentBoundary component, a new Label component, and improvements to QuickGrid. Blazor adds relative navigation, IHostedService support in WebAssembly, and OpenAPI schema support for binary file responses. SignalR includes new configuration options for interactive server components.
Client and data frameworks round out the release. .NET MAUI now uses XAML source generation by default, and .NET for Android moves to CoreCLR. Windows Forms and WPF focus on quality fixes. Entity Framework Core expands support for complex types, JSON columns, and TPT and TPC inheritance, while Azure Cosmos DB scenarios gain new features such as transactional batches and bulk execution.
Developers can install the .NET 11 SDK now, with support available in the latest Visual Studio 2026 Insiders build and in Visual Studio Code with the C# Dev Kit.
