Microsoft has released .NET 9, along with Visual Studio 2022 17.12 and updates to a host of associated frameworks and tools, including .NET Aspire, MAUI for cross-platform applications, ASP.NET Core and Blazor. The release is tied in with the virtual .NET Conf 2024, which is under way this week.

The .NET platform is extensive, including the C#, F# and Visual Basic .NET languages (though Visual Basic is near-frozen), frameworks for web, distributed, windows and cross-platform desktop and mobile applications, as well as libraries for database, AI and more.

At the first day of .NET Conf there was a notable focus on Aspire 9, the latest release of Microsoft’s toolkit for developing distributed applications. The new version works with both .NET 9 and .NET 8, which is important as .NET 8 is a long-term support release.

What is Aspire? It is not easy to explain since it has several distinct pieces. Aspire orchestration is for simplifying local development of distributed applications. Aspire integrations are packages for services which use a standardized interface and apply best-practice defaults including OpenTelemetry observation, health checks, and service discovery. Aspire tooling includes templates for Visual Studio and Visual Studio Code (VS Code). Finally, the Aspire Dashboard is a user interface to show the health of an Aspire application, mainly for use during development.

Aspire does have momentum, evidenced by growing numbers of integrations including for kafka, MongoDB, RabbitMQ, Node.js and PostgreSQL as well as Microsoft technologies. There is also a healthy amount of activity in its GitHub repository. At .NET Conf attendees were told of an internal project, a backend for Copilot, that was rebuilt using Aspire in just 4 months, with benefits including faster speed, smaller codebase, and improved scalability and reliability.

That said, Aspire remains strongly Microsoft-centric, with excellent support for Azure deployment and services and much less for others, though there is a .NET Conf session later this week on “Building .NET Applications Across Clouds” which mentions AWS.

That issue with Aspire highlights a core problem for the .NET stack, that while Microsoft’s sponsorship ensures its stability and evolution, the domination by one company also hurts broad adoption.

At .NET Conf Microsoft also highlighted improvements to MAUI (Multi-platform App UI), the framework for cross-platform applications targeting WinUI, Mac Catlyst, iOS and Android. Product Manager David Ortinau claimed the framework has seen a 30 percent increase in active users, and highlighted the arrival of a free toolkit for MAUI from component vendor Syncfusion. Attendees also learned that since July, 55 percent of community contributions to .NET MAUI have come from Syncfusion, suggesting perhaps the company found plenty that needed fixing or improving for its toolkit to work smoothly.

MAUI was widely considered not to be ready when first launched but may now be worth a second look. The introduction of a HybridWebView to the framework is another important advance. The top ask from developers, aside from reliability concerns, is Linux support, of which there is no sign yet.

Visual Studio 2022 17.12 has new features including editor refinements, new GitHub Copilot integrations, improved debugging for Blazor WebAssembly applications, Git tooling updates and more, though it would be wrong to describe this as a major release.

More information on what is new in .NET 9 can be found here – though note that this release is only supported until May 2026. The next long-term support release will be .NET 10, set for release this time next year.