.NET Core vs .NET Framework | What’s the Difference? (2024)

Key Points

• .NET Core and .NET Framework are two hugely popular and closely related development platforms that differ in approach and use cases
• The original .NET Framework remains relevant for legacy applications and Windows-centric development
• .NET Core is cross-platform, cloud-native, lightweight and modular, not to mention it provides excellent integration with Docker
• Microsoft changed the narrative in 2020 by creating a new unified .NET platform that includes .NET Core, .NET Framework, and Xamarin

With a history that spans back to 2002, Microsoft’s .NET is a flexible and scalable framework that provides developers with a rich set of tools and resources to build high-quality and scalable apps for everything from game development to machine learning or IoT.

And with more than 18% of devs  choosing it as their go-to framework, its relevance remains undisputed, as demonstrated by average annual salaries of nearly $100K for .NET developers that are actively seeking roles in the .NET job market.

But as we move deeper into 2024, how do you settle a debate like .NET Core vs .NET Framework? Is it simply that the .NET core is better for cross-platform development while the .NET framework is suited for Windows? 

Well, the answer to these questions is unclear, especially as Microsoft has completed its plan to unify the two into the simply named .NET 6.

Confused? No problem, let’s dive in to figure this all out!

What Is .NET Core?

.NET Core is an open-source and cross-platform development framework developed by Microsoft that’s known for being modern, lightweight, and modular. This means developers can build high-performance apps for various platforms, including Windows, Linux, and macOS.

Cross-platform support is one of the most important features of .NET Core, as it allows developers to write code that runs on different OS without the need for modifications. I can’t think of any dev that doesn’t appreciate the ability to write once and run anywhere (it’s not just Java that can claim this!).

This is made possible because .NET Core is a completely modular framework, meaning that developers can pick and choose the features to compile into their app.

Another key feature of .NET Core is high performance. This framework was designed to be fast and efficient. You also have multithreading and asynchronous programming support, allowing you to take full advantage of modern CPUs while achieving high scalability.

.NET Core also includes a rich set of libraries and tools that provide a wide range of web development, data access, security, and more functionalities. Again, these are all designed to be modular, meaning you need only use the parts of the framework you require.

You also get support for modern dev practices, including microservices, containerization, and DevOps. In fact, .NET Core has built-in support for Docker, making it super-easy for devs to package and deploy applications as containers to a range of environments.

In 2024, .NET Core has a thriving community of developers, helped by the fact that beyond C#, VB.NET, and F#, you can use a variety of popular languages like Java, Python, Ruby, and Go if you’re willing to install the necessary interop mechanisms and libraries.

And interestingly, Microsoft made the source code for .NET Core available under the MIT License, while .NET Core itself is free to download and use. 

What Is the .NET Framework?

Microsoft’s .NET Framework is a widely-used software development platform that provides a comprehensive set of tools, libraries, and runtime components for building and running applications on Windows-based systems. This is the key differentiator between .NET Framework and .NET Core.

.NET framework offers a rich development environment and supports the usual Microsoft programming languages of C#, VB.NET, and F#. Since 2002, .NET Framework has been widely adopted for developing a wide range of applications, from desktop software to web applications and services.

One of the key features of the .NET Framework is the Common Language Runtime (CLR) which is the execution engine for .NET applications. The CLR manages memory, handles garbage collection, and provides services like security, exception handling, and thread management.

The .NET framework also takes a ‘full batteries included’ approach, as it includes an extensive class library known as the Base Class Library (BCL), which provides a vast collection of reusable types and components. This offers huge functionality, including file I/O, networking, database access, cryptography, and UI development.

In general, the BCL hugely simplifies app development by providing a range of pre-built components and APIs, allowing devs to focus on business logic rather than low-level infrastructure.

Unsurprisingly, the .NET Framework has evolved a lot in the last 20 years, with the latest stable version .NET Framework 4.8, being released in April 2019. This has since received a range of bug fixes and patches but represents the last major update.

And while the .NET Framework continues to be used for many Windows-based apps, developers have been encouraged to migrate to .NET Core, or more accurately, the new unified .NET 5 and beyond, as this offers a modern and versatile ecosystem for building cross-platform apps that run on Windows, macOS, and Linux.

The Difference Between .NET Framework and .NET Core

Before we dive into the differences between .NET Core and the .NET Framework, it’s important to point out that Microsoft themselves have taken steps to group rather than divide its NET products.

In an effort to simplify branding and remove ongoing confusion regarding the difference between .NET Core and .NET Framework, Microsoft dropped the ‘Core’ branding with .NET 5 in November 2020. 

Does this mean there is no difference between .NET and .NET Core? Great question! This decision was a key part of Microsoft's effort to unify the .NET platform across .NET Core and .NET Framework. So it’s less helpful to pose questions like dotnet vs dotnet Core but more useful to consider this a larger narrative shift.

But what does this all mean?

Well, from .NET 5 onwards, we can now technically refer to a single .NET runtime and framework that can be used everywhere. Meaning that the full .NET framework is simply referred to as .NET, followed by the version.

Simply put, you can now use .NET 5, .NET 6, etc., which is a unified .NET platform that combines the best of .NET Core, .NET Framework, and even Xamarin and Mono. Microsoft’s goal was to provide a single platform that could be used for all types of .NET applications.

You can also build modern .NET applications on AWS. We found a helpful course on that topic.

That said, and for the time being, many of us view .NET Core and .NET Framework as separate entities. And as we saw above, there are several key differences between the two. Let’s take a look at a head-to-head to better understand these differences.

When comparing .NET Framework vs .Net Core, it's important to remember that they were designed in different eras with different use cases in mind.

When .NET Framework was released in 2002, web development was hugely important, but cloud services and microservices weren't anywhere near as dominant as they are now. Also, Windows was still the primary OS targeted by developers of business apps.

In the last two decades, we've seen a significant shift in how people work and where they store their data. Today, it's estimated that 94% of companies use or host at least one cloud service, smartphones are near-ubiquitous, and nearly 3% of desktop users run some form of Linux distribution.

Of course, Windows is still the dominant desktop OS by an enormous margin, with MacOS in a not-so-close second place, but an increasing number of developers are seeing the value of writing cross-platform applications.

The popularity of cloud hosting has also created a seismic shift in the way that developers work. Rather than building monolithic apps, microservice-based architectures have become hugely popular, as they make it easier to update, test and scale applications.

When it was first released, .NET Core was the newer and more modern version of .NET, and it was designed in a very different tech environment to the original .NET Framework.

Because of this, Microsoft was able to focus on flexible tools for application models, microservices support, and cross-platform support, not to mention a simpler solution for containerization via Docker support.

.NET vs .NET Core: Which Should You Use?

If you're a new developer and you're wondering which framework to focus on, the answer is most likely .NET Core. It’s newer, actively developed, and designed with the needs of modern developers in mind.

You can use .NET Core for virtually any development task, including:

• Microservices
• Mobile applications
• Websites and apps
• Cloud services
• Desktop applications
• Games
• Machine learning

Because .NET Core is designed with a ‘code once, run anywhere’ philosophy, you'll save lots of time developing apps on .NET Core. Just choose your preferred language, write your code, and build for multiple platforms from a single codebase.

Why Choose .NET Core Over .NET Framework?

Thanks to its cross-platform support, lightweight codebase, modularity, and cloud-native interoperability, .NET Core is a logical choice if you're working with microservices or plan on using Docker containers.

These core features (excuse the pun!) allow for efficient containerization as you only need to include the necessary components, reducing Docker image sizes and improving startup times.

What’s more, .NET Core makes it easy to create microservices with different languages, where each service will be an independent, lightweight process that does its job with minimal overhead. These can then be turned into Docker containers that have a very small footprint.

Now, you can use the .NET Framework for microservices and Docker containers, but in general, the relative experience would be best defined by bloated executables.

In contrast, .NET Core offers improved performance via Just-In-Time (JIT) compilation and optimized garbage collection, along with a natural alignment with modern DevOps practices and continuous integration/continuous deployment (CI/CD) pipelines.

Plus, with .NET Core being built with cloud-native development in mind, you also get seamless integration with modern cloud platforms and services like Kubernetes, Azure, and AWS.

And once again, modularity and containerization support make it super easy to leverage cloud services and scale microservices applications in a cloud-native environment with .NET Core.

Of course, when it comes to smaller applications, the additional overhead from the .NET Framework may seem trivial. Still, if you're running hundreds of microservices across multiple machines or VMs, extra overhead can add up quickly, meaning that .NET Core can offer noticeable performance improvements for web or cloud services.

The Case for the .NET Framework

Despite being the older sibling, there are scenarios when .NET Framework may be the better choice than its younger brother, .NET Core.

If your application is intended to run exclusively on Windows and does not require cross-platform compatibility, .NET Framework might be a good choice, as it has deep integration with the Windows OS and provides a wide range of features and APIs specific to Windows development.

If your application heavily relies on WCF for building distributed systems and service-oriented architectures, you get full-featured WCF support with .NET Framework versus limited WCF support in .NET Core.

.NET Framework offers support for WinForms and WPF for building desktop applications with rich UIs compared to MAUI (Multi-Platform App UI) with .NET Core, which lacks the same level of maturity and compatibility.

Finally, the .NET Framework has a mature ecosystem and extensive third-party library support. So, if your project heavily relies on specific libraries, components, or tools that are unavailable or compatible with .NET Core, it might be convenient to stick with .NET Framework.

The Unification of .NET Core & .NET Framework

It’s important to reiterate that Microsoft's own focus has shifted towards the unification of .NET Core with .NET Framework into the newest .NET 6.

So while it might seem like a marketing trick to simply drop the ‘Core’ branding, the long-term plan from Microsoft is to migrate its user base towards .NET 6 and any newer versions that have yet to be released.

The main goal here is to offer all .NET developers the advantages of modern dev practices, cross-platform support, improved performance, and better cloud integration. 

What does this all mean? Well, when you’re speccing new projects, considering long-term support, or considering future-proofing, rather than framing the question as .NET Core vs .NET Framework, Microsoft would prefer you to simply choose .NET 6.

It takes a little time to get used to the new naming conventions and the shift in mindset, but when you see .NET 5, .NET 6, or any newer versions, think of these as the best of both .NET Core and .NET Framework. 

Final Thoughts

Microsoft’s .NET Core and .NET Framework are two hugely popular and closely related development platforms that differ in approach, capabilities, and target use cases.

The younger .NET Core emphasizes modern development via cross-platform compatibility and cloud-native architectures, and it also offers the benefit of a lightweight codebase, modular components, strong performance, and excellent integration with containerization technologies like Docker.

The original .NET Framework continues to be relevant for existing applications and Windows-centric development as it offers a mature ecosystem, extensive third-party library support, and deep integration with Windows-specific features and APIs.

That said, Microsoft has switched gears to change the narrative from .NET Core vs .NET Framework to the unification of the .NET ecosystem, the result of which is a new unified .NET platform that includes .NET Core, .NET Framework, and Xamarin.

With this new unified approach, .NET devs should be able to streamline development, improve code sharing and portability, and provide a consistent programming model across different platforms.

Applying for web developer roles in .NET? Check out these:

ASP.NET Interview Questions & Answers

Frequently Asked Questions

1. Is .NET Core Replacing .NET Framework?

Microsoft's future focus has primarily shifted to .NET Core and the unified .NET platform, indicating that new features, enhancements, and innovations will primarily target .NET Core, while the .NET Framework will receive only limited updates and maintenance.

2. Why Is .NET Core Faster Than the .NET Framework?

The architecture of .NET Core is very different to that of .NET Framework. Because .NET Core is cross-platform, it's essentially a complete rewrite of .NET. That said, it was designed with performance in mind via just-in-time (JIT) compilation and improved garbage collection. .NET Core also has a lightweight and modular architecture, allowing for better resource utilization and reduced overhead.

3. When Should You Not Use .NET Core?

If you have existing applications built on the .NET Framework with extensive dependencies or reliance on Windows-specific APIs, it's a good idea to do a cost/benefits analysis before trying to port it to .NET Core. Also, if your project is Windows-only or you rely heavily on WCF features and bindings that are not supported in Core WCF, .NET Framework may be a better choice.

4. When Is It Wise to Not Run .NET Framework?

If cross-platform compatibility is a requirement or you’re starting a new project and prefer a lightweight, modular, and cloud-native development approach, using .NET Core or the unified .NET platform is recommended instead of the .NET Framework.

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