JSON to TypeScript

Generate a TypeScript interface or type from a JSON sample for API responses, mock data, frontend models, tests, and quick prototypes. Choose the root type name and copy the inferred definition into your project.

How JSON types are inferred

• Strings, numbers, booleans, arrays, and nested objects become TypeScript types.
• Mixed arrays use a union of the value types found in the sample.
• Empty arrays become unknown[], and null values become unknown.
• A top-level array of objects generates an interface plus a list type.

Sample-based generation limits

The output describes the values present in one sample; it cannot discover fields that are optional or missing from that sample. For a top-level array, the first item is used as the interface shape. Review optional properties, nullable fields, date strings, and API-specific unions before using the result in production.

This generator creates static TypeScript definitions, not runtime validation. Use a JSON Schema validator when you also need to verify incoming data.

Related tools: JSON Formatter · JSON Schema Validator