How do I deserialize a JSON array to a List?

Use JsonSerializer.Deserialize >(jsonString) where Root is your generated class. The List property types are generated automatically.

JSON to C# Class

Generate C# classes with System.Text.Json or Newtonsoft.Json attributes from any JSON object.

Root class name

JSON Input

C# Output

What is C# JSON Serialization?

In C#, JSON serialization converts between C# objects (classes, records, structs) and JSON strings. The .NET ecosystem has two main serializers: System.Text.Json (built-in since .NET Core 3.0, preferred for new projects) and Newtonsoft.Json (the classic library, still dominant in older codebases).

When consuming REST APIs in ASP.NET Core or calling external services, you typically define C# model classes that match the JSON structure. The serializer handles conversion automatically when you use JsonSerializer.Deserialize<T>() or HttpClient.GetFromJsonAsync<T>(). This tool generates the complete class hierarchy from your JSON instantly.

System.Text.Json vs Newtonsoft.Json

Feature	System.Text.Json	Newtonsoft.Json
Attribute	[JsonPropertyName]	[JsonProperty]
Package	Built into .NET 3+	Newtonsoft.Json NuGet
Performance	Faster (span-based)	Slower but more flexible
Null handling	Explicit nullable	More lenient
Best for	.NET 6+ / ASP.NET Core	Legacy / complex scenarios

Example: System.Text.Json Output

csharp

using System.Text.Json.Serialization;
using System.Collections.Generic;

public class Address
{
    [JsonPropertyName("street")]
    public string Street { get; set; }

    [JsonPropertyName("city")]
    public string City { get; set; }
}

public class Root
{
    [JsonPropertyName("id")]
    public long Id { get; set; }

    [JsonPropertyName("name")]
    public string Name { get; set; }

    [JsonPropertyName("address")]
    public Address Address { get; set; }
}

Deserialize with System.Text.Json

csharp

using System.Text.Json;

var root = JsonSerializer.Deserialize<Root>(jsonString);
// Or with options:
var options = new JsonSerializerOptions { PropertyNameCaseInsensitive = true };
var root2 = JsonSerializer.Deserialize<Root>(jsonString, options);

Type Mapping

JSON Type	C# Type	Notes
string	string	Nullable reference type
integer	long	Avoids int overflow
float	double	Double precision
boolean	bool	Non-nullable
null	object?	Nullable object
array	List<T>	System.Collections.Generic
object	class	New named C# class

Frequently Asked Questions

Use System.Text.Json for all new .NET 6+ projects. It's built-in, faster, and the default for ASP.NET Core minimal APIs and controllers.

Use JsonSerializer.Deserialize<List<Root>>(jsonString) where Root is your generated class. The List<T> property types are generated automatically.

For System.Text.Json — no, it's included in .NET 3+. For Newtonsoft.Json — install Newtonsoft.Json from NuGet.

Each property gets a [JsonPropertyName] or [JsonProperty] attribute with the original name. No configuration needed.

Yes — the generated classes are plain C# POCOs. You can use them as EF entity classes by adding navigation properties and [Key] attributes.

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JSON Schema Generator

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