TypeScript interfaces provide compile-time type safety. When working with API responses or JSON data, manually writing interfaces is tedious. This tool analyzes JSON and generates accurate TypeScript interfaces with proper types for strings, numbers, booleans, arrays, nested objects, and nullable fields.
Paste a JSON object or array into the input field and TypeScript interfaces are generated automatically. The tool analyzes every property, infers its type (string, number, boolean, null, array, or nested object), and creates properly named interfaces. You can customize the root interface name. Nested objects are extracted into separate named interfaces. The output can be copied or downloaded as a .ts file.
JSON-to-TypeScript conversion saves significant development time when working with REST APIs - paste an API response and instantly get type-safe interfaces. It is commonly used for typing API response data in frontend applications, generating types from database schemas exported as JSON, creating interfaces from mock data during rapid prototyping, building type-safe SDK clients for third-party APIs, and ensuring compile-time safety when working with configuration files.
The type inference algorithm recursively traverses the JSON structure: primitive values map to their TypeScript types (string, number, boolean), null maps to null, arrays analyze all elements to determine the union element type, and nested objects generate separate named interfaces in PascalCase. When analyzing JSON arrays, the tool compares all objects to identify optional fields (present in some but not all objects) and marks them with the ? modifier. Union types are generated when array elements have mixed types.
Paste a JSON object or array into the input. The tool analyzes every property, infers its type, and generates a complete TypeScript interface. Nested objects get their own named interfaces.
If you provide a JSON array, the tool uses the first object element to generate the interface. For arrays of objects, it creates a separate type alias (e.g., RootArray = Root[]).
Yes. Nested objects are extracted into separate named interfaces and referenced by name. For example, a 'user' property with an object value generates a separate User interface.
Yes. You can set a custom name for the root interface. Child interfaces are named automatically based on the property name in PascalCase.
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