How to Convert an object to JSON in C#

You can easily perform serialization using one of two main options:

• Use JsonSerializer.Serialize() (from System.Text.Json).
• Use JsonConvert.SerializeObject() (from Newtonsoft.Json).

Below, I'll walk through examples using both methods.

Using JsonSerializer.Serialize() (from System.Text.Json)

For example, how you can serialize an object with System.Text.Json using the JsonSerializer.Serialize() method:

using System.Text.Json;

var book = new Book()
{
    Title = "1984",
    Author = "George Orwell",
    Pages = 328,
    PublishDate = new DateTime(year: 1949, month: 6, day: 8),
    IsBestseller = true
};

var json = JsonSerializer.Serialize(book);

In this example, the Book object is serialized into a JSON string using the default settings. The output would look like this:

{"Title":"1984","Author":"George Orwell","Pages":328,"PublishDate":"1949-06-08T00:00:00","IsBestseller":true}

Customizing Serialization with JsonSerializerOptions

You can modify the default behavior of serialization by passing in a JsonSerializerOptions object.

For example, here’s how to pretty-print the JSON:

var options = new JsonSerializerOptions()
{
    WriteIndented = true
};

var json = JsonSerializer.Serialize(book, options);

This will output the JSON in a more readable format:

{
  "Title": "1984",
  "Author": "George Orwell",
  "Pages": 328,
  "PublishDate": "1949-06-08T00:00:00",
  "IsBestseller": true
}

Using JsonConvert.SerializeObject() (from Newtonsoft.Json)

If you prefer to use the Newtonsoft.Json package, you first need to install it via NuGet:

Install-Package Newtonsoft.Json

Once installed, here’s how to serialize an object with JsonConvert.SerializeObject():

using Newtonsoft.Json;

var book = new Book()
{
    Title = "1984",
    Author = "George Orwell",
    Pages = 328,
    PublishDate = new DateTime(year: 1949, month: 6, day: 8),
    IsBestseller = true
};

var json = JsonConvert.SerializeObject(book, Formatting.Indented);

This will produce the following JSON output:

{
  "Title": "1984",
  "Author": "George Orwell",
  "Pages": 328,
  "PublishDate": "1949-06-08T00:00:00",
  "IsBestseller": true
}

Notice the use of Formatting.Indented to pretty-print the JSON.

Customizing Serialization with JsonSerializerSettings

To further customize the serialization, you can pass a JsonSerializerSettings object. For instance, to convert property names to camel case while also pretty-printing:

using Newtonsoft.Json;
using Newtonsoft.Json.Serialization;

var settings = new JsonSerializerSettings()
{
    ContractResolver = new CamelCasePropertyNamesContractResolver(),
    Formatting = Formatting.Indented
};

var person = new Person() { FirstName = "John", LastName = "Doe" };

var json = JsonConvert.SerializeObject(person, settings);

This generates the following JSON:

{
  "firstName": "John",
  "lastName": "Doe"
}

Whether you choose System.Text.Json or Newtonsoft.Json, both libraries provide simple and powerful ways to serialize objects to JSON. You can also customize the serialization process by using options or settings to suit your application's needs.