When it comes to developing software applications, there are different .NET frameworks you can use. Two of the most talked about are .NET Core and .NET Framework. While they share similarities, there are key differences that affect which one you should choose for your projects.
This article will help you understand .NET Core, .NET Framework, and .NET Standard—what each one is, how they differ, and when to use each. By the end, you'll have a clear picture of the .NET ecosystem and be able to make informed decisions for your applications.
.NET Core is a cross-platform, open-source, and modular .NET platform for creating modern applications. It works on Windows, Linux, and macOS, making it ideal for web apps, microservices, cloud applications, and IoT solutions.
Microsoft built .NET Core from the ground up to be lightweight and flexible. It includes the runtime, framework libraries, compiler, and other tools you need to build and run applications. The platform is distributed as NuGet packages, which means you can include only what you need—keeping your apps lean.
Key characteristics of .NET Core:
.NET Framework is Microsoft's original Windows-only platform for building desktop apps, web applications, and services. It's been around since 2002 and includes a massive class library called the Framework Class Library (FCL). This library provides pre-built functionality for common programming tasks.
.NET Framework runs only on Windows and is closed-source. It's deeply integrated with Windows, which makes it powerful for Windows-specific development but limits its reach to other operating systems.
Key characteristics of .NET Framework:
.NET Core runs on multiple platforms (Windows, Linux, macOS), while .NET Framework only runs on Windows. If you need your application to work on non-Windows systems, .NET Core is your only choice.
.NET Core is fully open-source with active community involvement. You can view the source code, contribute fixes, and even fork it for custom needs. .NET Framework is closed-source, though some parts have been open-sourced over time.
.NET Core supports side-by-side installation—you can have multiple versions installed on the same machine, and each app can use its own version. .NET Framework uses a machine-wide installation, which can cause compatibility issues when different apps need different framework versions.
.NET Core is best for modern apps: web applications (ASP.NET Core), microservices, cloud apps, and cross-platform solutions. .NET Framework is ideal for traditional Windows apps: WinForms desktop applications, WPF, Windows Services, and ASP.NET Web Forms.
.NET Core is generally faster and more efficient than .NET Framework. Microsoft has optimized it for modern workloads and cloud environments, resulting in better throughput and lower memory usage.
.NET Standard isn't a runtime or a way to write code—it's a specification. Think of it as a contract that defines which APIs all .NET platforms must support. When you target .NET Standard, your code can run on any .NET platform that implements that version of the standard.
Before .NET Standard, code written for .NET Framework wouldn't necessarily work on .NET Core because they had different APIs. .NET Standard solved this problem by creating a common set of APIs that all platforms agree to support.
Why .NET Standard matters:
To use .NET Standard, you target a specific version when creating your library. The current version is 2.1, which includes many features that weren't in earlier versions like support for ASP.NET Core and Entity Framework Core.
Higher .NET Standard versions include more APIs but work on fewer platforms. Lower versions have fewer APIs but broader compatibility. You need to balance the features you need against the platforms you want to support.
.NET Core is the modern, cross-platform, open-source evolution of .NET. .NET Framework is the Windows-only, mature platform that's been around for decades. .NET Standard is the specification that allows code to work across both.
For new projects, Microsoft recommends using .NET Core (now called just ".NET" from version 5 onward). It gets active development, runs anywhere, and provides the best performance. Use .NET Framework only when you have specific requirements that demand it, such as maintaining legacy code or using Windows-specific features not available in modern .NET.
.NET Core is cross-platform and open-source, running on Windows, Linux, and macOS. .NET Framework is Windows-only and closed-source. .NET Core supports side-by-side installation and is more modular, while .NET Framework targets traditional Windows applications.
.NET Standard is a set of APIs that all .NET platforms must implement. It allows you to write code once that works across .NET Framework, .NET Core, Xamarin, and other .NET platforms without modification, solving the compatibility problem between different .NET implementations.
For new projects, use modern .NET (formerly .NET Core). It's cross-platform, gets active updates, has better performance, and is Microsoft's recommended path forward. Only use .NET Framework if you have specific dependencies that require it or need Windows-specific features unavailable in modern .NET.