JSON to Python Pydantic Model Generator Online

Convert JSON payloads into clean Python BaseModel classes with type hints (str, int, float, List[T], Optional[T]) and Field(alias=...) support for FastAPI and Django.

Open JSON to Pydantic Generator →

Sample Input JSON

{
  "user_id": 101,
  "user_name": "alex",
  "is_active": true,
  "roles": ["admin", "editor"]
}

Generated Pydantic v2 Model

from typing import List
from pydantic import BaseModel

class UserModel(BaseModel):
    user_id: int
    user_name: str
    is_active: bool
    roles: List[str]

Pydantic V2 Ready

Generates clean PEP-8 snake_case attributes with Field alias definitions.

FastAPI Support

Ideal for building request/response validation schemas in Python web services.

Local & Offline

Runs locally in your browser with zero network requests.

Frequently Asked Questions

How do I convert JSON to Python Pydantic v2 models online?

Paste any JSON payload into JSON OS. The type inference engine scans nested objects, primitive types, and arrays to generate idiomatic Pydantic BaseModel classes.

Does JSON OS keep my payloads private?

Yes. JSON OS processes everything 100% locally in your browser using Web Workers without sending payloads to external servers.