3 min read

The Evolution of .NET Project Files: .csproj vs. project.json

Let's see why the evolution of the project.json and .csproj.
The Evolution of .NET Project Files: .csproj vs. project.json
Photo by Nick Fewings / Unsplash


Developers who work with .NET projects often come across different project file formats such as .csproj, .fsproj, .vbproj, project.json, etc.

These files are at the core of the project structure and hold essential information about dependencies, configurations, and build settings.

However, when .NET Core 1.0 came out, most developers saw the benefits of project.json, and it became out of the picture when .NET Core 2.0 was released, and Microsoft decided to stick with .csproj.

That’s why, in this article, we'll explore the evolution of .NET project files, focusing on two key formats: project.json and .csproj.

What is project.json?

The project.json was introduced in the early stages of .NET Core development to replace the traditional .csproj project files used in the .NET Framework.

Don't get me wrong, I love .csproj.

Let’s try to see what project.json problems it solves.

1. Simplified Configuration

The primary goal of project.json was to streamline project configuration. That's why it is using a JSON format, which is more human-readable and more accessible to work with than the XML-based .csproj files.

This simplification made it more approachable for developers, especially those new to the .NET ecosystem.

2. Dependency Management

The project.json introduced a fresh approach to dependency management.

It allowed developers to specify dependencies directly in the JSON file, making it clear and concise. As a result, it simplified package management and made it easier to manage project references.

3. Cross-Platform Compatibility

As a part of the .NET Core initiative, project.json it was designed to be cross-platform. This meant projects project.json could be developed and run on various platforms, including Windows, Linux, and macOS.

What Version of .NET Did Project.json Come Out?

Its first appearance was in the early versions of .NET Core, specifically in versions before .NET Core 1.0.

It was an integral part of the project system for a few years, during which it earned praise and criticism from the developer community.

The Transition: project.json to .csproj

Despite its initial promise and advantages, project.json it eventually faced a significant change in the .NET Core ecosystem.

When and Why Was It Replaced?

In .NET Core 1.0 and 1.1, project.json the primary project file format was used.

However, it was replaced by .csproj when .NET Core 2.0 came out.

Several key factors drove the decision; let's try to see them one by one.

1. Compatibility and Ecosystem Concerns

One of the issues with project.json was compatible with existing libraries and components.

Meaning that existing .NET libraries and tools were built around the .csproj format. This transition created friction when trying to incorporate these existing components into .NET Core projects.

2. Tooling Support

The tooling support for project.json was not as mature as that for .csproj.

Popular development environments like Visual Studio had extensive support for .csproj files, which provided a better development experience. That's why the decision to revert to .csproj was partly to improve the tooling experience for developers.

3. Standardization

The transition back to .csproj was also aimed at standardizing the project file format across different .NET projects.

This made it easier for developers to work with different types of .NET projects and contributed to a more consistent development experience.

Can We Still Use project.json Today?

As of .NET Core 2.0 and beyond, project.json has been officially deprecated and is no longer a supported project file format.

All new .NET projects should use the .csproj format.

However, it's important to note that existing projects using project.json can still be maintained and upgraded, but it's recommended to migrate to .csproj for the best compatibility and tooling support.


The journey from project.json to .csproj reflects the ever-evolving nature of software development and the .NET ecosystem.

While project.json aimed to simplify project configuration and dependency management, it ultimately faced compatibility, tooling support, and standardization challenges.

Today, .csproj is the primary project file format for .NET projects because it offers better compatibility, extensive tooling support, and a standardized approach to project management.

Developers working on .NET projects are encouraged to embrace .csproj for a more streamlined and compatible development experience.