Microsoft has launched .NET 9, introducing advanced features designed to streamline application development, particularly for AI integration and cross-platform solutions. Described as the most efficient, secure, and high-performing version to date, .NET 9 brings substantial improvements in speed, security, and functionality, offering developers a more powerful and seamless experience.

Microsoft .NET 9.0 is now generally available for download

Microsoft’s new .NET 9, released, has many improvements over its predecessor .NET 8. It’s built with a focus on performance and cloud-native apps. .NET 9 will be supported for 18 months as standard-term support. Below are some of the new implementations on .NET 9.

.NET runtime

The .NET 9 runtimes have a new attribute model for feature switches with trimming support. It makes it easy to define feature switches that libraries can use to toggle areas of functionality.

The runtimes include numerous improvements in performance like loop optimizations, inlining, Arm64 vectorization, and code generation.

.NET libraries

The .NET libraries include many new libraries. System.Text.Json adds support for nullable reference type annotations and exports JSON schemas from types. New libraries like CountBy, AggregateBy, GroupBy, etc., are included with performance improvements.

.NET SDK

The .NET 9 SDK comes with a workload sets feature where all the workload stays in the single, specific version until you manually update it. A dotnet tool install option, lets users select the tools that are allowed to run on a newer .NET runtimes version. .NET SDK comes with features including Unit testing with better MSBuild integration, NuGet security audit, terminal logger, New MSBuild script analyzers, etc.

AI building blocks

.NET 9 has a new unified layer of C# abstractions via Microsoft.Extensions.AI and Microsoft.Extensions.VectorData packages. These abstractions enable the interaction with AI services including small and large language models.

.NET Aspire

To make it easier to build observable and production-ready apps, .NET Aspire has powerful tools, templates, and packages with improvements to the dashboard and resource lifecycle management. It brings more flexibility in development by enabling the addition of new integration and APIs during development.

There are other new improvements like ASP.NET Core for security and support, .NET MAUI for multi-platform support and enhanced performance, reliability, and deeper integrations, EF Core, C# 13, F# 9, Windows Presentation Foundation, and Windows Forms. Microsoft has confirmed it in its blog about .NET 9.