If you worked with earlier versions of ASP.NET MVC and ASP.NET Core, you are probably aware that these versions use Json.NET library for the sake of JSON processing. In ASP.NET Core 3 Microsoft has provided in-built support for JSON serialization and deserialization. That means you no longer need to depend on Json.NET library. The good part is, you can still use Json.NET if you so wish. So, you have two options now as far as JSON processing is concerned - either use in-built JSON API or use Json.NET. The in-built support for JSON serialization and deserialization comes from System.Text.Json namespace. In this article you will learn to use the System.Text.Json for serializing and deserializing JSON data during Web API communication.