Working with YAML in C# (.NET): Libraries and Usage Examples

Working with YAML in C# (.NET): Libraries and Practical Examples

YAML (YAML Ain't Markup Language) is a popular data serialization format widely used for configuration files, DevOps (Ansible, Kubernetes, Docker Compose), and data exchange. The .NET ecosystem does not have built-in YAML support, but there are powerful third-party libraries. In this article, we will look at two main ones: YamlDotNet (the most popular) and SharpYaml (a lightweight alternative), and show how to integrate them into C# projects.

1. Why Choose YAML over JSON/XML?

• Human-readable syntax with indentation (no brackets or quotes).
• Support for comments (starting with #).
• Built-in support for complex structures (lists, dictionaries, multi-line strings).
• De facto standard for configurations in containerization and CI/CD.

2. Main Library: YamlDotNet

YamlDotNet is the most mature and maintained library for .NET (including .NET Core, .NET 5+). It provides a full cycle: deserialization (YAML → C# objects) and serialization (objects → YAML).

2.1 Installation via NuGet

dotnet add package YamlDotNet

Or via the Visual Studio package manager: Install-Package YamlDotNet.

2.2 Basic Deserialization

Suppose we have a file config.yaml:

# Application settingsapp:  name: MyApp  version: 1.0.0  debug: false

database:  host: localhost  port: 5432  credentials:    user: admin    password: secret

Let's create the corresponding C# classes:

public class AppConfig{    public string Name { get; set; }    public string Version { get; set; }    public bool Debug { get; set; }}

public class DatabaseConfig{    public string Host { get; set; }    public int Port { get; set; }    public Credentials Credentials { get; set; }}

public class Credentials{    public string User { get; set; }    public string Password { get; set; }}

public class RootConfig{    public AppConfig App { get; set; }    public DatabaseConfig Database { get; set; }}

Now let's parse YAML into objects:

using YamlDotNet.Serialization;using YamlDotNet.Serialization.NamingConventions;

var yamlContent = File.ReadAllText("config.yaml");

var deserializer = new DeserializerBuilder()    .WithNamingConvention(UnderscoredNamingConvention.Instance) // for underscores    .Build();

var config = deserializer.Deserialize<RootConfig>(yamlContent);

Console.WriteLine($"App: {config.App.Name} v{config.App.Version}");Console.WriteLine($"DB host: {config.Database.Host}:{config.Database.Port}");

2.3 Serializing Objects to YAML

var serializer = new SerializerBuilder()    .WithNamingConvention(CamelCaseNamingConvention.Instance)    .Build();

var config = new RootConfig{    App = new AppConfig { Name = "TestApp", Version = "2.0.0", Debug = true },    Database = new DatabaseConfig    {        Host = "192.168.1.1",        Port = 3306,        Credentials = new Credentials { User = "root", Password = "qwerty" }    }};

string yamlOutput = serializer.Serialize(config);Console.WriteLine(yamlOutput);

2.4 Working with Dynamic Data

If the YAML structure is unknown in advance, use Dictionary<object, object>:

var deserializer = new DeserializerBuilder()    .Build();

var result = deserializer.Deserialize<Dictionary<object, object>>(yamlContent);// Recursive dictionary traversalPrintYaml(result, 0);

void PrintYaml(Dictionary<object, object> dict, int indent){    foreach (var kvp in dict)    {        Console.WriteLine($"{new string(' ', indent * 2)}{kvp.Key}: {kvp.Value}");