Runs locally in your browser
JSON to Python Dataclass Converter
Turn sample JSON into typed Python dataclasses. Nested objects, arrays, null values, and fields missing from array items are inferred automatically.
✓ Python dataclasses generated automatically in your browser
How to convert JSON to Python dataclasses
- Paste a representative JSON object or array.
- Set a descriptive root class name.
- Keep future annotations enabled for modern, flexible type references.
- Copy or download the generated Python module.
How JSON values map to Python
| JSON value | Generated annotation | Important detail |
|---|---|---|
| Integer / decimal | int / float | Inferred from the sample number |
| Object | Nested dataclass | Receives a readable class name |
| Array | list[T] | Multiple items improve type inference |
| Value plus null | T | None | Nullable fields default to None |
Dataclasses describe shape, not trust
Generated annotations reflect only the supplied sample. Objects inside the same array are compared so fields missing from some items can become optional. Field names are converted to valid Python identifiers, including handling keywords and names that need snake_case normalization.
Dataclasses do not parse or validate an API response automatically. Load the JSON, construct the objects deliberately, and add runtime validation—such as explicit checks or a validation library—when data comes from an external system or user input.
Frequently asked questions
Which Python types are generated?
JSON strings, integers, decimals, booleans, arrays, objects, and null values become str, int, float, bool, list, nested dataclasses, and optional union types.
Why are nested dataclasses generated?
Each nested object gets a named dataclass so the resulting model remains readable, type-checkable, and easy to extend.
Does this validate API responses at runtime?
No. Dataclass annotations help static analysis but do not validate untrusted data. Add explicit parsing and validation for production API inputs.
Does the JSON leave my browser?
No. Conversion runs entirely on your device.