What’s New in .NET 9: A Beginner-Friendly Overview

4 min read3 days ago

.NET 9 is here, and it’s packed with features that make building applications faster, more powerful, and easier. From improved performance to new tools for AI, .NET 9 has a lot to offer for developers at all levels. In this article, we’ll break down the key highlights of .NET 9 in simple terms, so you can get a quick idea of how it can benefit your projects.

What’s Special About .NET 9?

.NET 9, the follow-up to .NET 8, is designed with a focus on cloud-native apps (apps that are built to work in the cloud) and performance. It’s also a standard-term support release, meaning it will receive official support for 18 months.

1. Improved .NET Runtime

The runtime is the core of .NET, where code runs. Here are the main updates:

Feature Switches: Developers can now turn certain features on or off more easily, making it simpler to trim down unnecessary parts of an app.
Better Garbage Collection (GC): GC is how .NET cleans up unused memory. Now, it can adjust automatically based on how big or small an app is, making it more efficient.
Faster Code Execution: .NET 9 optimizes code execution, especially on ARM processors, which are often found in mobile devices.

2. Enhanced .NET Libraries

Libraries are tools that help developers perform common tasks. Key updates include:

System.Text.Json: This library, used to handle JSON data, now has more ways to customize and control data format. It can also produce JSON schema files, which help in validating JSON data.
LINQ Improvements: New features allow grouping and counting data more easily, which is especially useful when working with large data sets.
Priority Queue Updates: The priority queue can now update the priority of items, which is helpful when managing data that frequently changes in importance.
New TimeSpan Methods: These methods let you create time intervals using whole numbers, making them easier to work with.

3. Updates to the .NET SDK

The Software Development Kit (SDK) includes all the tools you need to build .NET applications. New features here:

Workload Sets: This lets you keep all your tools at the same version, preventing version mismatches in large projects.
Enhanced Testing: Testing tools now run faster and support running tests at the same time, which is great for speeding up development.
Security Checks: The SDK now audits packages you use to ensure they’re secure.
Improved Build Logs: You get more detailed feedback on build warnings and errors, making it easier to troubleshoot issues.

4. AI and Machine Learning (ML) Support

.NET 9 brings exciting new tools for developers working with AI:

AI Libraries: The Microsoft.Extensions.AI library makes it easier to integrate AI services, from simple machine learning models to large language models.
Tensor Updates: Tensors are a tool for handling large sets of data in AI tasks. With new improvements, you can perform mathematical operations on tensors faster and with fewer resources.
ML.NET 4.0: ML.NET, the .NET machine learning framework, now allows you to load certain models as streams (making it faster) and improves the handling of text data.

5. ASP.NET Core: For Web Apps

ASP.NET Core is a tool in .NET for building web applications. In .NET 9, it brings:

Static File Optimization: Static files (like JavaScript or CSS) are now handled faster and can be auto-versioned to prevent caching issues.
New Templates for Blazor: Blazor lets you build interactive web pages. The new templates make it easier to get started with different kinds of web projects.
Enhanced Security: New APIs make it easier to manage secure access in web apps.
Better Development on Linux: Setting up HTTPS (secure connection) during development is easier on Linux.

6. .NET MAUI: For Mobile and Desktop Apps

.NET MAUI (Multi-platform App UI) is .NET’s toolkit for building mobile and desktop apps. Updates in .NET 9:

Faster Performance: Controls like CollectionView and CarouselView (used to show lists and images) are now quicker, especially on iOS.
New Desktop Features: There’s a new TitleBar control for Windows desktop apps and a HybridWebView that makes it easy to show web content.
Simpler Page Management: A new way of setting up the main page for your app, making code cleaner and more manageable.

7. Updates for C# 13 and F# 9

.NET 9 includes new versions of the programming languages C# 13 and F# 9:

C# 13: Brings simpler ways to work with collections, manage memory, and handle specific data types.
F# 9: Adds support for nullable reference types (which help avoid errors with null values) and other performance improvements.

8. Windows Presentation Foundation (WPF) and Windows Forms

For desktop apps, WPF and Windows Forms also received updates:

WPF: Adds support for light and dark themes and uses Windows’ Fluent design theme, so apps look more modern.
Windows Forms: Now supports async dialog methods and some dark mode options, which are experimental but bring modern features to classic Windows Forms apps.

Final Thoughts

.NET 9 brings a lot of improvements that make developing apps easier and faster. Whether you’re working on web, mobile, desktop, or AI-powered applications, there’s something in .NET 9 to make your development process smoother and more efficient.

To learn more about any specific feature, check out the official Microsoft documentation. Dive in, and happy coding!