Free JSON Schema to TypeScript Converter

JSON Schema is a declarative language that allows you to annotate and validate JSON documents. It describes the structure, data types, and constraints of JSON data, making it possible to automatically validate whether a JSON document conforms to the expected format.

JSON data is actual content (like a user record), while JSON Schema is a specification that describes what valid JSON data should look like. This tool converts the schema (the specification) into TypeScript type definitions, not data into TypeScript.

The tool generates TypeScript interfaces for object types, type aliases for primitives and unions, JSDoc comments from descriptions, optional fields based on the required array, discriminated unions from anyOf/oneOf, and intersection types from allOf. Nested objects become separate interfaces with auto-generated names.

Paste your JSON Schema document into the input panel on the left, then click "Generate Types" to convert it to TypeScript interface definitions. Use "Load Sample" to try a comprehensive example, and click the copy icon or "Copy Output" to copy the generated TypeScript to your clipboard.

JSON to TypeScript tools generate types from example JSON data (inferring structure). This tool generates TypeScript from JSON Schema, which is a formal specification. Schema-based generation is more precise because schemas explicitly declare types, constraints, optional fields, enums, references, and union types that cannot be inferred from example data alone.

The tool will display an error message indicating the JSON parse error. Please check your JSON syntax and try again. Common issues include trailing commas, unquoted keys, and mismatched brackets.

Circular $ref references occur when Schema A references Schema B, which directly or indirectly references Schema A again. This tool detects circular references and generates TypeScript that uses optional or recursive type annotations. In TypeScript, recursive types can be expressed using interfaces with self-referencing properties. However, deeply nested or complex circular references may require manual adjustment of the generated output to avoid infinite type instantiation errors.

This tool accepts JSON Schema, which is the core of OpenAPI's schema definitions. You can extract the schema components from an OpenAPI specification's components.schemas section and paste each schema individually. For full OpenAPI-to-TypeScript conversion, consider dedicated tools like openapi-typescript or swagger-typescript-api, which handle paths, operations, response types, and request bodies holistically across the entire API specification.

This tool supports JSON Schema Draft-04, Draft-07, and Draft 2020-12, which are the most widely used versions. Draft-04 introduced the $ref keyword and is used by OpenAPI 2.0. Draft-07 added if/then/else conditional validation and is the standard for OpenAPI 3.0. Draft 2020-12 introduced $defs (replacing definitions) and formal vocabulary support. The converter handles format differences between drafts, such as keyword deprecations and additions.

JSON Schema format keywords like date-time, email, uri, and ipv4 provide semantic validation hints but do not change the underlying type (all are strings). This converter generates string TypeScript types and includes the format constraint as a JSDoc comment. For strict typing, you can use TypeScript's template literal types or branded types to enforce format validation at the type level, but this requires manual post-processing of the generated output.