Saule

Saule is a JSON API (version 1.0) library for ASP.Net Web API 2. Install Saule using NuGet:

Install-Package saule

Visit the documentation website

To use Saule, you must define resources that contain the information about your domain:

public class PersonResource : ApiResource
{
    public PersonResource()
    {
        Attribute("FirstName");
        Attribute("LastName");
        Attribute("Age");

        BelongsTo<CompanyResource>("Job");
        HasMany<PersonResource>("Friends");
    }
}
public class CompanyResource : ApiResource
{
    public CompanyResource()
    {
        Attribute("Name");
        Attribute("NumberOfEmployees");
    }
}

You can then use these to serialize any class into Json Api (as long as your class has properties with the same names as in your model):

public class PersonController : ApiController
{
    [HttpGet]
    [ReturnsResource(typeof(PersonResource))]
    [Route("people/{id}")]
    public JohnSmith GetPerson(string id)
    {
        return new JohnSmith();
    }
}

GET http://example.com/people/123

{
  "data": {
    "type": "person",
    "id": "123",
    "attributes": {
      "first-name": "John",
      "last-name": "Smith",
      "age": 34
    },
    "relationships": {
      "job": {
        "links": {
          "self": "http://example.com/people/123/relationships/job/",
          "related": "http://example.com/people/123/job/"
        },
        "data": {
          "type": "company",
          "id": "456"
        }
      },
      "friends": {
        "links": {
          "self": "http://example.com/people/123/relationships/friends/",
          "related": "http://example.com/people/123/friends/"
        },
        "data": [
          {
            "type": "person",
            "id": "789"
          }
        ]
      }
    }
  },
  "included": [
    {
      "type": "company",
      "id": "456",
      "attributes": {
        "name": "Awesome, Inc.",
        "number-of-employees": 24
      }
    },
    {
      "type": "person",
      "id": "789",
      "attributes": {
        "first-name": "Sara",
        "last-name": "Jones",
        "age": 38
      }
    }
  ],
  "links": {
    "self": "http://example.com/people/123"
  }
}

Deserialization works just like in normal Web API; you don't need to do anything special to make this work.