JSON to Python Dataclass

Paste JSON and generate clean, ready-to-paste Python dataclasses with nested models, type hints, and optional datetime-aware fields.

Root Class Name

Detect datetime

Treat ISO-8601 strings as datetime.

Use future annotations

Adds from __future__ import annotations.

Use Optional types

Wrap nullable or missing fields in Optional[...].

Use list default factories

Emit field(default_factory=list) for required lists.

Convert fields to snake_case

Keeps Python field names idiomatic and comments original JSON keys.

Use slots=True

Generate slimmer dataclass instances.

Use frozen=True

Generate immutable dataclass objects.

Use kw_only=True

Make generated dataclass arguments keyword-only.

Input JSON

Your generated Python dataclasses will appear here.

Mixed-type arrays and inconsistent sample shapes fall back to Any when a safe, more specific Python type cannot be inferred.

No. Everything runs in your browser, so your JSON stays on your device.

Nullable or missing fields can be wrapped in Optional[...] and default to None in the generated dataclass.

Yes. Root arrays generate a typed alias like AutoGenerated = list[AutoGeneratedItem].

Yes. ISO-8601 datetime strings can be inferred as datetime and the tool adds the correct import automatically.