Microsoft Releases .NET 9

As promised, Microsoft today released .NET 9, the latest version of its free and open-source application platform. The release is timed to the company’s annual .NET Conf virtual event, which is underway now.

“.NET 9 is the most productive, modern, secure, intelligent, and performant release of .NET yet,” the .NET team writes in the announcement post. “It’s the result of another year of effort on the part of thousands of developers from around the world. This new release includes thousands of performance, security, and functional improvements. You will find sweeping enhancements across the entire .NET stack from the programming languages, developer tools, and workloads enabling you to build with a unified platform and easily infuse your apps with AI.”

.NET 9 brings over 1,000 performance-related changes across its runtime, workloads, languages, and app types, a new version of the .NET Aspire cloud distributed app framework, new AI capabilities across the stack (including, among other things, C# abstractions for small and large language models (SLMs and LLMs), embeddings, vector stores, middleware, and other AI services), GitHub Copilot enhancements, and updated versions of ASP.NET Core, Blazor, .NET MAUI, C#, F#,  Visual Studio, and even Windows desktop development.

Obviously, I’m most interested in that last bit. The WPF support for Windows 11 theming in .NET 9 is a bit half-baked, but the new documentation is up, and there are some improvements, including some I’ve asked for. More on that soon.

” With .NET 9, your Windows apps will have access to the latest OS features and capabilities while ensuring they are more performant and accessible than ever before,” Microsoft notes. “Whether you are starting a new modern app with WinUI 3 and the Windows App SDK or modernizing your existing WPF and WinForms applications, your Windows apps run best on .NET 9. We have been collaborating closely with the Windows developer community to bring features that you have been requesting. This includes Native AOT support for WinUI 3 for smaller and more performant apps, modern theming enhancements with Fluent UI for WPF, and WinForms gets a boost with a new Dark Mode, modern icon APIs, and improved asynchronous API access.”

New, up-to-date downloads for Visual Studio 2022 (17.12) and .NET 9 will be available today, Microsoft says. (It looks like they’re not up yet, as I write this.)