JSON to C# Class Generator

No. Type inference and code generation run entirely in your browser, so you can paste production payloads, internal API contracts, or customer data without them leaving your machine.

Use System.Text.Json for new .NET projects. It ships with the runtime, it's faster, and ASP.NET Core uses it by default. Pick Newtonsoft.Json when the project already depends on it, for example older ASP.NET MVC code or libraries that expose JObject. The attributes keep the original JSON key, so snake_case or other naming styles still map onto PascalCase properties.

A property becomes nullable when the sample has a null for it, or when it's missing from some of the objects in an array. Value types (int, bool, DateTime, Guid) always get the ? in that case. With Nullable reference types on, string, list, and class properties are annotated too, and the ones that are always present get an initializer (string.Empty, [], or new()), so the code compiles without CS8618 warnings.

Types come from the sample you paste. A price that happens to be 250 in every item reads as an integer, and JSON itself doesn't distinguish 250 from 250.0. Add an item with a fractional value, or change the property to decimal by hand. For money, set Decimals to decimal so fractional numbers never become double.

If the root is an array of objects, the items are merged into one class and a comment tells you to deserialize as List<Root>. When a property holds different kinds of values across items (a number in one, a string in another), it becomes object, because there's no single C# type that fits. Numbers that mix whole and fractional values widen to double or decimal instead.