CMD Simulator

Nested Objects – JSON to Typedef Example

See how deeply nested JSON objects are converted into separate TypeScript interfaces or C# classes. Each level gets its own named type.

What this demonstrates: This example demonstrates 5 levels of nesting. The converter creates separate named types for each nested object: Company, Headquarters, Address, Country, Coordinates, Ceo, and Contact. Each type is properly referenced by its parent.

JSON Input
TypeScript Output

Paste JSON on the left to generate typedefs

Supports Nested Objects and Arrays

Our converter recursively processes deeply nested JSON structures, including arrays of objects, mixed-type arrays, and multi-level object hierarchies. Each nested object gets its own named interface (TypeScript) or class (C#) with properly typed properties.

Optional Fields and Mixed Types Handled

When a field is null in your JSON, it's automatically marked as optional in TypeScript (with ?) or nullable in C#. Arrays with mixed element types produce union types or fallback to object.

How to Use This JSON to Typedef Converter

1

Paste JSON

Paste or type your JSON into the input area on the left.

2

Choose Language

Select TypeScript or C# from the dropdown.

3

Copy Output

Your type definitions appear instantly. Click Copy to use them.

More Examples

Arrays of ObjectsConvert JSON arrays containing objects into properly typed arrays with dedicated interfaces. See how element types are inferred from array contents.Mixed Types & Union TypesSee how the converter handles mixed-type arrays and fields with different value types, producing union types in TypeScript and object fallback in C#.Null Values & Optional FieldsDemonstrate how null values in JSON are converted to optional fields in TypeScript (?) and nullable types in C# (?). Essential for API response typing.REST API ResponseConvert a real-world REST API response with pagination, nested resources, and metadata into typed interfaces. A practical example for frontend developers.E-Commerce Product DataConvert complex e-commerce product JSON with variants, pricing, inventory, and reviews into clean type definitions for online store development.
Next →Arrays of Objects