JSON to TypeScript Converter
Generate typed interfaces for nested objects and arrays without sending your JSON anywhere.
Lines
18
Types
3
Chars
279
JSON input
TypeScript output
TypeScript generated
TypeScript definitions generated from the current JSON sample.
export interface ApiResponse {
id: number;
name: string;
active: boolean;
owner: Owner;
features: FeaturesItem[];
}
export interface Owner {
name: string;
email: string;
}
export interface FeaturesItem {
name: string;
enabled?: boolean;
released?: string;
}Objects in the same array are merged, and fields missing from some items become optional.
Convert JSON into TypeScript Types
JSON to TypeScript conversion turns a representative JSON value into interfaces and type aliases that can be used in an application, API client, test fixture, or data pipeline. The converter detects strings, numbers, booleans, null values, nested objects, and arrays.
Objects inside the same array are combined into one item interface. A property that appears in only some array items is marked optional, while shared properties remain required. You can also make every property optional or add readonly to generated fields.
When to Generate Types from JSON
- Create a starting type for an API response or webhook payload.
- Describe fixture data before adding it to a TypeScript project.
- Identify inconsistent fields across objects in a sample array.
- Replace repeated inline object types with named interfaces.
Generated types describe the sample you provide, not every value an API may return. Review nullable fields, optional properties, date strings, enums, and error responses before relying on the output in production.
Use the JSON Formatter to repair or inspect a payload first. To define runtime validation rules from the same sample, use the JSON Schema Generator.