How to create JSON string in C#

I just used the XmlWriter to create some XML to send back in an HTTP response. How would you create a JSON string. I assume you would just use a stringbuilder to build the JSON string and them format your response as JSON?


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Method 1

Using Newtonsoft.Json makes it really easier:

Product product = new Product();
product.Name = "Apple";
product.Expiry = new DateTime(2008, 12, 28);
product.Price = 3.99M;
product.Sizes = new string[] { "Small", "Medium", "Large" };

string json = JsonConvert.SerializeObject(product);

Documentation: Serializing and Deserializing JSON

Method 2

You could use the JavaScriptSerializer class, check this article to build an useful extension method.

Code from article:

namespace ExtensionMethods
    public static class JSONHelper
        public static string ToJSON(this object obj)
            JavaScriptSerializer serializer = new JavaScriptSerializer();
            return serializer.Serialize(obj);

        public static string ToJSON(this object obj, int recursionDepth)
            JavaScriptSerializer serializer = new JavaScriptSerializer();
            serializer.RecursionLimit = recursionDepth;
            return serializer.Serialize(obj);


using ExtensionMethods;


List<Person> people = new List<Person>{
                   new Person{ID = 1, FirstName = "Scott", LastName = "Gurthie"},
                   new Person{ID = 2, FirstName = "Bill", LastName = "Gates"}

string jsonString = people.ToJSON();

Method 3

Simlpe use of Newtonsoft.Json and Newtonsoft.Json.Linq libraries.

        //Create my object
        var myData = new
            Host = @"",
            UserName = "my_username",
            Password = "my_password",
            SourceDir = "/export/zip/mypath/",
            FileName = ""

        //Tranform it to Json object
        string jsonData = JsonConvert.SerializeObject(myData);

        //Print the Json object

        //Parse the json object
        JObject jsonObject = JObject.Parse(jsonData);

        //Print the parsed Json object

Method 4

This library is very good for JSON from C#

Method 5

This code snippet uses the DataContractJsonSerializer from System.Runtime.Serialization.Json in .NET 3.5.

public static string ToJson<T>(/* this */ T value, Encoding encoding)
    var serializer = new DataContractJsonSerializer(typeof(T));

    using (var stream = new MemoryStream())
        using (var writer = JsonReaderWriterFactory.CreateJsonWriter(stream, encoding))
            serializer.WriteObject(writer, value);

        return encoding.GetString(stream.ToArray());

Method 6

You can also try my ServiceStack JsonSerializer it’s the fastest .NET JSON serializer at the moment. It supports serializing DataContracts, any POCO Type, Interfaces, Late-bound objects including anonymous types, etc.

Basic Example

var customer = new Customer { Name="Joe Bloggs", Age=31 };
var json = JsonSerializer.SerializeToString(customer);
var fromJson = JsonSerializer.DeserializeFromString<Customer>(json);

Note: Only use Microsofts JavaScriptSerializer if performance is not important to you as I’ve had to leave it out of my benchmarks since its up to 40x-100x slower than the other JSON serializers.

Method 7

If you need complex result (embedded) create your own structure:

class templateRequest
    public String[] registration_ids;
    public Data data;
    public class Data
        public String message;
        public String tickerText;
        public String contentTitle;
        public Data(String message, String tickerText, string contentTitle)
            this.message = message;
            this.tickerText = tickerText;
            this.contentTitle = contentTitle;

and then you can obtain JSON string with calling

List<String> ids = new List<string>() { "id1", "id2" };
templateRequest request = new templeteRequest();
request.registration_ids = ids.ToArray(); = new templateRequest.Data("Your message", "Your ticker", "Your content");

string json = new JavaScriptSerializer().Serialize(request);

The result will be like this:

json = "{"registration_ids":["id1","id2"],"data":{"message":"Your message","tickerText":"Your ticket","contentTitle":"Your content"}}"

Hope it helps!

Method 8

Take a look at for the json-net.aspx project. Why re-invent the wheel?

Method 9

If you can’t or don’t want to use the two built-in JSON serializers (JavaScriptSerializer and DataContractJsonSerializer) you can try the JsonExSerializer library – I use it in a number of projects and works quite well.

Method 10

If you want to avoid creating a class and create JSON then Create a dynamic Object and Serialize Object.

            dynamic data = new ExpandoObject();
   = "kushal";
            data.isActive = true;

            // convert to JSON
            string json = Newtonsoft.Json.JsonConvert.SerializeObject(data);

Read the JSON and deserialize like this:

            // convert back to Object
            dynamic output = Newtonsoft.Json.JsonConvert.DeserializeObject(json);

            // read a particular value:

ExpandoObject is from System.Dynamic namespace.

Method 11

If you’re trying to create a web service to serve data over JSON to a web page, consider using the ASP.NET Ajax toolkit:

It will automatically convert your objects served over a webservice to json, and create the proxy class that you can use to connect to it.

Method 12

The DataContractJSONSerializer will do everything for you with the same easy as the XMLSerializer. Its trivial to use this in a web app. If you are using WCF, you can specify its use with an attribute. The DataContractSerializer family is also very fast.

Method 13

I’ve found that you don’t need the serializer at all. If you return the object as a List.
Let me use an example.

In our asmx we get the data using the variable we passed along

// return data
[WebMethod(CacheDuration = 180)]
public List<latlon> GetData(int id) 
    var data = from p in 
               where == id 
               select new latlon
                   lat =,
                   lon = p.lon

    return data.ToList();

public class latlon
    public string lat { get; set; }
    public string lon { get; set; }

Then using jquery we access the service, passing along that variable.

// get latlon
function getlatlon(propertyid) {
var mydata;

    url: "getData.asmx/GetLatLon",
    type: "POST",
    data: "{'id': '" + propertyid + "'}",
    async: false,
    contentType: "application/json;",
    dataType: "json",
    success: function (data, textStatus, jqXHR) { //
        mydata = data;
    error: function (xmlHttpRequest, textStatus, errorThrown) {
return mydata;

// call the function with your data
latlondata = getlatlon(id);

And we get our response.


Method 14

Encode Usage

Simple object to JSON Array EncodeJsObjectArray()

public class dummyObject
    public string fake { get; set; }
    public int id { get; set; }

    public dummyObject()
        fake = "dummy";
        id = 5;

    public override string ToString()
        StringBuilder sb = new StringBuilder();

        return sb.ToString();

dummyObject[] dummys = new dummyObject[2];
dummys[0] = new dummyObject();
dummys[1] = new dummyObject();

dummys[0].fake = "mike";
dummys[0].id = 29;

string result = JSONEncoders.EncodeJsObjectArray(dummys);


Pretty Usage

Pretty print JSON Array PrettyPrintJson() string extension method

string input = "[14,4,[14,"data"],[[5,""],[6,""]]]";
string result = input.PrettyPrintJson();

Results is:


Method 15


using System.Text.Json;

Then serialize your object_to_serialize like this:

All methods was sourced from or, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0

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