Convert JSON to Python
dict, dataclass,
Pydantic or TypedDict.
Generate Python dataclasses, Pydantic v2 models, TypedDicts and json.loads() code from any JSON sample. Optional fields, List[T] arrays, nested classes. Runs entirely in your browser.
Optional[Any] — refine manually after generating.
Four Python patterns — choose based on your use case and Python version.
| Style | Python | Runtime validation | Best for |
|---|---|---|---|
| Dict | Any | None | Quick scripts, prototypes. json.loads() returns a dict — access with data["key"]. Zero dependencies. |
| dataclass | 3.7+ | None (type hints only) | Structured data containers in production code. Works with asdict() for re-serialization. Built-in, no pip. |
| Pydantic v2 | 3.8+ | Yes — fast (Rust core) | APIs, config parsing, CLI tools. Validates types at runtime, generates JSON Schema, OpenAPI compatible. |
| TypedDict | 3.8+ | None (static only) | Adding types to dict-based code without adding dependencies. Works with mypy, pyright, Pylance. |
| JSON value | Python type | Notes |
|---|---|---|
"Alice" | str | All JSON strings become str. |
42 | int | JSON integers become int. |
98.5 | float | JSON floats become float. |
true | bool | Direct mapping. |
null | Optional[Any] | Null → Optional[Any]. Refine the type manually after generating. |
["a","b"] | List[str] | Item type inferred from first element. Empty → List[Any]. |
[{…},{…}] | List[ChildClass] | Array of objects → separate class + typed List. |
{…} | ChildClass | Nested object → separate named class in PascalCase. |
FastAPI request bodies and response models require Pydantic BaseModel classes. Generate the model from a real API payload JSON sample — then use model_validate_json() to deserialize incoming requests. Pydantic v2 validates types, raises clear errors and generates OpenAPI schema automatically.
When consuming a REST API in Python, json.loads() returns a plain dict — accessing nested fields with string keys is error-prone. Generate a dataclass or TypedDict from a real response sample to get IDE autocomplete and static type checking across the response structure.
Configuration files in JSON format (pyproject.json, .vscode/settings.json, API config files) need typed Python representations for safe access. Generate a Pydantic model for runtime validation — any misconfigured value raises a clear ValidationError with the field name and expected type.
pytest tests that call API endpoints need typed response objects for assertion. Generate a TypedDict from the expected response structure — then use cast() to tell mypy the json.loads() result has the right shape, getting autocomplete in tests without a runtime dependency.
Python generated in
your browser. No upload.
The entire Python code generation runs in JavaScript locally. Your JSON is parsed and traversed entirely in your browser — it is never transmitted to any server. The generated code follows Python conventions: snake_case field names, correct Optional syntax, and proper import statements for each style.
The Pydantic v2 output uses the new API — model_validate_json(), model_dump_json(), BaseModel with model_config — not the deprecated Pydantic v1 methods (.json(), .dict()) that most generators still produce.
