How are nested objects handled?

Each nested object gets its own named interface derived from the property's key (converted to PascalCase), and the parent interface references it by name — so you get a clean set of separate, reusable interfaces instead of one deeply inlined type.

What happens with arrays of objects that have different fields?

The converter merges the fields seen across all objects in the array into a single interface, so every field that appears in any item is represented. It doesn't currently mark fields as optional based on which items are missing them — review the output if your array items vary a lot.

What type does `null` get?

A JSON `null` becomes the TypeScript `null` type. If a field is sometimes a value and sometimes null across different objects, you may want to manually union it with the other type it takes.

Is my JSON sent anywhere?

No. The conversion runs locally in your browser with JavaScript — nothing is transmitted or stored.

JSON TO TYPESCRIPT CONVERTER

Turn any JSON into clean TypeScript interfaces. Nothing leaves your browser.

JSON input

Root type name

TypeScript interfaces

interface RootAddress {
  city: string;
  zip: string;
}

interface Root {
  id: number;
  name: string;
  active: boolean;
  tags: string[];
  address: RootAddress;
  scores: number[];
}

How to use the JSON to TypeScript converter

1
Paste a JSON object or array.
2
Optionally rename the root interface.
3
Read the generated TypeScript interfaces, including any nested objects as their own interfaces.
4
Copy the result straight into your .ts or .d.ts file.

Questions

How are nested objects handled?: Each nested object gets its own named interface derived from the property's key (converted to PascalCase), and the parent interface references it by name — so you get a clean set of separate, reusable interfaces instead of one deeply inlined type.
What happens with arrays of objects that have different fields?: The converter merges the fields seen across all objects in the array into a single interface, so every field that appears in any item is represented. It doesn't currently mark fields as optional based on which items are missing them — review the output if your array items vary a lot.
What type does `null` get?: A JSON `null` becomes the TypeScript `null` type. If a field is sometimes a value and sometimes null across different objects, you may want to manually union it with the other type it takes.
Is my JSON sent anywhere?: No. The conversion runs locally in your browser with JavaScript — nothing is transmitted or stored.