How to Generate TypeScript Interfaces or Python Dataclasses from JSON

When to use the JSON to Code generator

When you have JSON from an API, configuration file, or sample payload, JSON to Code can turn that text into a starting type definition. It supports TypeScript interfaces and Python dataclasses. TypeScript is selected by default, while Python is available when you want dataclass declarations instead.

The input must be JSON text rather than an informal object description. A useful workflow is to prepare one representative JSON object, choose the target language, and give the generated root type a name that fits your project. Nested objects are represented by nested generated types, so the resulting structure can reflect more than the top-level fields.

How to generate a TypeScript interface or Python dataclass

1. Prepare the JSON you want to convert. Remove surrounding explanations, comments, or other text so the input contains JSON. If the formatting is difficult to read, use the related JSON Beautifier first.

2. Paste the JSON into the input area. Do not leave the field blank or fill it with whitespace, because the generator needs supplied JSON text.

3. Choose a language. Keep TypeScript selected for interface declarations, or choose Python for dataclass declarations. Values in the JSON guide the generated field types: strings map to string in TypeScript and str in Python, booleans map to boolean and bool, and numbers map to number and float.

4. Set the root type name if you want something other than Root. Use a name that describes the top-level object, such as Customer, Order, or Product.

5. Run the conversion and review the generated result. Check that the structure matches the JSON you supplied, especially where nested objects appear.

6. If the conversion fails, first verify that the input is not blank and that it is valid JSON. Also check that the selected language is TypeScript or Python.

How to read the generated result

For a JSON object, a TypeScript result uses interface declarations, with fields inferred from the values in the input. A Python result uses dataclass declarations with fields inferred in the same way. Nested objects receive their own generated types, and fields that point to those objects use the corresponding nested types.

Treat the result as a structured starting point based on the JSON you provided. If the payload changes, generate again from the updated shape and review the output. A malformed payload does not produce a conversion, and a language outside the two supported choices is rejected rather than interpreted as another target.

Worked example

A developer has a customer payload containing a name, an active flag, an account number, and a nested address object and wants a Python type definition for that payload.

Paste the JSON, choose Python, set the root type name to Customer, and run the conversion.

A TypeScript selection produces interface declarations for the top-level object and its nested object. The fields use string, boolean, and number for the supplied string, boolean, and numeric values. A Python selection produces dataclass declarations with str, bool, and float fields.

Limitations

• Only TypeScript and Python are supported targets; another selected language is rejected.
• Blank input and malformed JSON do not produce a generated result.

Common errors

• The input is blank or not valid JSON: paste a JSON value without surrounding prose, then check its punctuation and structure before running the conversion.

FAQ

Can I generate a TypeScript interface from JSON?

Yes, when the input is valid JSON. TypeScript is selected by default and the result uses interface declarations for JSON objects.

Can I generate Python dataclasses from JSON?

Yes. Select Python instead of the default TypeScript option; JSON objects are represented with dataclass declarations.

Can I rename the generated root type?

Yes, if the input is valid and not blank. A custom root type name can be provided instead of the default Root.