Neat trick to convert JSON to a C# class in Visual Studio.

json2csharp.txt

1. Copy some JSON to your clipboard. Need some JSON? Here you go http://goo.gl/mWZSEL
2. In Visual Studio, right-click your project and select Add->Class.
3. Highlight the following code in your class:
class Class1
{
}
4. From the top menu, select Edit->Paste Special->Paste JSON as Classes.
5. Rename "Rootobject" to your desired class name. Done!

pets.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ClassLibrary1
{
    public class Rootobject
    {
        public string swagger { get; set; }
        public Info info { get; set; }
        public string host { get; set; }
        public string basePath { get; set; }
        public string[] schemes { get; set; }
        public string[] consumes { get; set; }
        public string[] produces { get; set; }
        public Paths paths { get; set; }
        public Definitions definitions { get; set; }
    }

    public class Info
    {
        public string version { get; set; }
        public string title { get; set; }
        public string description { get; set; }
        public string termsOfService { get; set; }
        public Contact contact { get; set; }
        public License license { get; set; }
    }

    public class Contact
    {
        public string name { get; set; }
    }

    public class License
    {
        public string name { get; set; }
    }

    public class Paths
    {
        public Pets pets { get; set; }
        public PetsId petsid { get; set; }
    }

    public class Pets
    {
        public Get get { get; set; }
        public Post post { get; set; }
    }

    public class Get
    {
        public string description { get; set; }
        public string operationId { get; set; }
        public string[] produces { get; set; }
        public Parameter[] parameters { get; set; }
        public Responses responses { get; set; }
    }

    public class Responses
    {
        public _200 _200 { get; set; }
        public Default _default { get; set; }
    }

    public class _200
    {
        public string description { get; set; }
        public Schema schema { get; set; }
    }

    public class Schema
    {
        public string type { get; set; }
        public Items items { get; set; }
    }

    public class Items
    {
        public string _ref { get; set; }
    }

    public class Default
    {
        public string description { get; set; }
        public Schema1 schema { get; set; }
    }

    public class Schema1
    {
        public string _ref { get; set; }
    }

    public class Parameter
    {
        public string name { get; set; }
        public string _in { get; set; }
        public string description { get; set; }
        public bool required { get; set; }
        public string type { get; set; }
        public Items1 items { get; set; }
        public string collectionFormat { get; set; }
        public string format { get; set; }
    }

    public class Items1
    {
        public string type { get; set; }
    }

    public class Post
    {
        public string description { get; set; }
        public string operationId { get; set; }
        public string[] produces { get; set; }
        public Parameter1[] parameters { get; set; }
        public Responses1 responses { get; set; }
    }

    public class Responses1
    {
        public _2001 _200 { get; set; }
        public Default1 _default { get; set; }
    }

    public class _2001
    {
        public string description { get; set; }
        public Schema2 schema { get; set; }
    }

    public class Schema2
    {
        public string _ref { get; set; }
    }

    public class Default1
    {
        public string description { get; set; }
        public Schema3 schema { get; set; }
    }

    public class Schema3
    {
        public string _ref { get; set; }
    }

    public class Parameter1
    {
        public string name { get; set; }
        public string _in { get; set; }
        public string description { get; set; }
        public bool required { get; set; }
        public Schema4 schema { get; set; }
    }

    public class Schema4
    {
        public string _ref { get; set; }
    }

    public class PetsId
    {
        public Get1 get { get; set; }
        public Delete delete { get; set; }
    }

    public class Get1
    {
        public string description { get; set; }
        public string operationId { get; set; }
        public string[] produces { get; set; }
        public Parameter2[] parameters { get; set; }
        public Responses2 responses { get; set; }
    }

    public class Responses2
    {
        public _2002 _200 { get; set; }
        public Default2 _default { get; set; }
    }

    public class _2002
    {
        public string description { get; set; }
        public Schema5 schema { get; set; }
    }

    public class Schema5
    {
        public string _ref { get; set; }
    }

    public class Default2
    {
        public string description { get; set; }
        public Schema6 schema { get; set; }
    }

    public class Schema6
    {
        public string _ref { get; set; }
    }

    public class Parameter2
    {
        public string name { get; set; }
        public string _in { get; set; }
        public string description { get; set; }
        public bool required { get; set; }
        public string type { get; set; }
        public string format { get; set; }
    }

    public class Delete
    {
        public string description { get; set; }
        public string operationId { get; set; }
        public Parameter3[] parameters { get; set; }
        public Responses3 responses { get; set; }
    }

    public class Responses3
    {
        public _204 _204 { get; set; }
        public Default3 _default { get; set; }
    }

    public class _204
    {
        public string description { get; set; }
    }

    public class Default3
    {
        public string description { get; set; }
        public Schema7 schema { get; set; }
    }

    public class Schema7
    {
        public string _ref { get; set; }
    }

    public class Parameter3
    {
        public string name { get; set; }
        public string _in { get; set; }
        public string description { get; set; }
        public bool required { get; set; }
        public string type { get; set; }
        public string format { get; set; }
    }

    public class Definitions
    {
        public Pet Pet { get; set; }
        public Newpet NewPet { get; set; }
        public Errormodel ErrorModel { get; set; }
    }

    public class Pet
    {
        public string type { get; set; }
        public Allof[] allOf { get; set; }
    }

    public class Allof
    {
        public string _ref { get; set; }
        public string[] required { get; set; }
        public Properties properties { get; set; }
    }

    public class Properties
    {
        public Id id { get; set; }
    }

    public class Id
    {
        public string type { get; set; }
        public string format { get; set; }
    }

    public class Newpet
    {
        public string type { get; set; }
        public string[] required { get; set; }
        public Properties1 properties { get; set; }
    }

    public class Properties1
    {
        public Name name { get; set; }
        public Tag tag { get; set; }
    }

    public class Name
    {
        public string type { get; set; }
    }

    public class Tag
    {
        public string type { get; set; }
    }

    public class Errormodel
    {
        public string type { get; set; }
        public string[] required { get; set; }
        public Properties2 properties { get; set; }
    }

    public class Properties2
    {
        public Code code { get; set; }
        public Message message { get; set; }
    }

    public class Code
    {
        public string type { get; set; }
        public string format { get; set; }
    }

    public class Message
    {
        public string type { get; set; }
    }

}

pets.json

{
  "swagger": "2.0",
  "info": {
    "version": "1.0.0",
    "title": "Swagger Petstore",
    "description": "A sample API that uses a petstore as an example to demonstrate features in the swagger-2.0 specification",
    "termsOfService": "http://swagger.io/terms/",
    "contact": {
      "name": "Swagger API Team"
    },
    "license": {
      "name": "MIT"
    }
  },
  "host": "petstore.swagger.io",
  "basePath": "/api",
  "schemes": [
    "http"
  ],
  "consumes": [
    "application/json"
  ],
  "produces": [
    "application/json"
  ],
  "paths": {
    "/pets": {
      "get": {
        "description": "Returns all pets from the system that the user has access to",
        "operationId": "findPets",
        "produces": [
          "application/json",
          "application/xml",
          "text/xml",
          "text/html"
        ],
        "parameters": [
          {
            "name": "tags",
            "in": "query",
            "description": "tags to filter by",
            "required": false,
            "type": "array",
            "items": {
              "type": "string"
            },
            "collectionFormat": "csv"
          },
          {
            "name": "limit",
            "in": "query",
            "description": "maximum number of results to return",
            "required": false,
            "type": "integer",
            "format": "int32"
          }
        ],
        "responses": {
          "200": {
            "description": "pet response",
            "schema": {
              "type": "array",
              "items": {
                "$ref": "#/definitions/Pet"
              }
            }
          },
          "default": {
            "description": "unexpected error",
            "schema": {
              "$ref": "#/definitions/ErrorModel"
            }
          }
        }
      },
      "post": {
        "description": "Creates a new pet in the store.  Duplicates are allowed",
        "operationId": "addPet",
        "produces": [
          "application/json"
        ],
        "parameters": [
          {
            "name": "pet",
            "in": "body",
            "description": "Pet to add to the store",
            "required": true,
            "schema": {
              "$ref": "#/definitions/NewPet"
            }
          }
        ],
        "responses": {
          "200": {
            "description": "pet response",
            "schema": {
              "$ref": "#/definitions/Pet"
            }
          },
          "default": {
            "description": "unexpected error",
            "schema": {
              "$ref": "#/definitions/ErrorModel"
            }
          }
        }
      }
    },
    "/pets/{id}": {
      "get": {
        "description": "Returns a user based on a single ID, if the user does not have access to the pet",
        "operationId": "findPetById",
        "produces": [
          "application/json",
          "application/xml",
          "text/xml",
          "text/html"
        ],
        "parameters": [
          {
            "name": "id",
            "in": "path",
            "description": "ID of pet to fetch",
            "required": true,
            "type": "integer",
            "format": "int64"
          }
        ],
        "responses": {
          "200": {
            "description": "pet response",
            "schema": {
              "$ref": "#/definitions/Pet"
            }
          },
          "default": {
            "description": "unexpected error",
            "schema": {
              "$ref": "#/definitions/ErrorModel"
            }
          }
        }
      },
      "delete": {
        "description": "deletes a single pet based on the ID supplied",
        "operationId": "deletePet",
        "parameters": [
          {
            "name": "id",
            "in": "path",
            "description": "ID of pet to delete",
            "required": true,
            "type": "integer",
            "format": "int64"
          }
        ],
        "responses": {
          "204": {
            "description": "pet deleted"
          },
          "default": {
            "description": "unexpected error",
            "schema": {
              "$ref": "#/definitions/ErrorModel"
            }
          }
        }
      }
    }
  },
  "definitions": {
    "Pet": {
      "type": "object",
      "allOf": [
        {
          "$ref": "#/definitions/NewPet"
        },
        {
          "required": [
            "id"
          ],
          "properties": {
            "id": {
              "type": "integer",
              "format": "int64"
            }
          }
        }
      ]
    },
    "NewPet": {
      "type": "object",
      "required": [
        "name"
      ],
      "properties": {
        "name": {
          "type": "string"
        },
        "tag": {
          "type": "string"
        }
      }
    },
    "ErrorModel": {
      "type": "object",
      "required": [
        "code",
        "message"
      ],
      "properties": {
        "code": {
          "type": "integer",
          "format": "int32"
        },
        "message": {
          "type": "string"
        }
      }
    }
  }
}

Excellent example, yes, we can easily convert JSON to C# class using paste special in VS
If anyone want to convert it using online tools check Online JSON to C# Class Converter

Wow, I can't beleive I didn't know about this. Thanks