Developer tools
JSON to Pydantic Model

JSON to Pydantic model converter

Paste a JSON payload and generate clean Python BaseModel classes with typing annotations for FastAPI, data pipelines, or LLM structured outputs — all computed locally on your machine.

Open JSON to Pydantic Model — free Get the Windows app

Free in your browser — no sign-up. Install from the Microsoft Store to use it offline on Windows 10 and 11.

How to use it

Open the JSON tool and paste your sample JSON.
Select Convert to → Python (Pydantic).
Copy the generated BaseModel classes into your Python project.

Example

JSON input

{
  "user_id": 101,
  "username": "ada",
  "is_admin": true,
  "tags": ["ml", "math"]
}

Python Pydantic output

from typing import List
from pydantic import BaseModel

class Root(BaseModel):
    user_id: int
    username: str
    is_admin: bool
    tags: List[str]

Features

Pydantic BaseModel classes with accurate int, float, str, bool, and List annotations. PRO
Nested model extraction — nested JSON objects automatically become separate child BaseModel classes.
Optional fields support — toggle Optional[...] annotations in one click.

Frequently asked questions

Is my JSON uploaded to generate Pydantic models?

No. Everything runs locally in your browser or the CodeForge Windows app.

Does it support nested JSON objects and arrays?

Yes. Nested objects are extracted into their own named BaseModel classes in PascalCase.

One workspace for all of it

JSON to Pydantic Model is one of 18 developer tools in CodeForge — alongside a JSON formatter, JWT decoder, regex tester, UUID and hash generators, and more. Press Ctrl+K to jump to any of them.