Monorepository with C#: Code Organization for .NET Projects

Monorepo with C#: Code Organization and Best Practices

In modern C# (.NET) development, the monorepo approach is increasingly used. Unlike multi-repositories, where each project lives in its own Git repository, a monorepo stores all company or product code in one central repository. For .NET developers, this means a single solution, shared libraries, and simplified CI/CD setup. In this article, we will look at how to properly organize a monorepo with C#, provide code examples, and discuss key advantages.

1. Advantages of a Monorepo for .NET

A monorepo is especially useful for teams working on multiple related .NET projects: microservices, web applications, class libraries. Main benefits:

• Single version of dependencies — all projects use the same versions of NuGet packages, eliminating conflicts.
• Simplified refactoring — changing a common interface or data model is immediately applied to all consumers.
• Shared Git history — atomic commits affecting multiple projects are visible in one place.
• Centralized CI/CD — one pipeline for building, testing, and deploying all components.

For C#, a monorepo is built around a single .sln file (solution) that references all projects. This allows using built-in Visual Studio and .NET CLI tools for dependency management.

2. Monorepo Structure for C#

Let's consider a typical monorepo structure for a .NET solution. It might look like this:

MyCompany/├── src/│   ├── MyCompany.Common/          # Shared library│   │   ├── MyCompany.Common.csproj│   │   └── ...│   ├── MyCompany.WebApi/          # Web API│   │   ├── MyCompany.WebApi.csproj│   │   └── ...│   └── MyCompany.BackgroundJob/   # Background service│       ├── MyCompany.BackgroundJob.csproj│       └── ...├── tests/│   ├── MyCompany.Common.Tests/│   ├── MyCompany.WebApi.Tests/│   └── MyCompany.BackgroundJob.Tests/├── docs/                         # Documentation├── scripts/                      # Scripts for CI/CD├── .gitignore└── MyCompany.sln                 # Single solution

Key elements of this structure:

• src/ — folder with source code. Each project is a separate folder with its own .csproj file.
• tests/ — folder with tests. Test project names mirror the main ones with the .Tests suffix.
• docs/ — documentation (README, architectural decisions).
• scripts/ — scripts for build or deployment automation.
• MyCompany.sln — single solution file that includes all projects.

This structure simplifies navigation and allows easily adding new projects without changing the root configuration.

3. Setting Up a Single Solution and Shared Dependencies

To create a monorepo in .NET, use the dotnet new sln command, then add projects:

# Create root folder and navigate into itmkdir MyCompany && cd MyCompany

# Create empty solution filedotnet new sln -n MyCompany

# Create folder structuremkdir src tests docs scripts

# Create projectsdotnet new classlib -n MyCompany.Common -o src/MyCompany.Commondotnet new webapi -n MyCompany.WebApi -o src/MyCompany.WebApidotnet new console -n MyCompany.BackgroundJob -o src/MyCompany.BackgroundJob

# Add projects to solutiondotnet sln add src/MyCompany.Common/MyCompany.Common.csprojdotnet sln add src/MyCompany.WebApi/MyCompany.WebApi.csprojdotnet sln add src/MyCompany.BackgroundJob/MyCompany.BackgroundJob.csproj

Now let's add a reference to the shared library from the Web API: