Convert JSON to Python Pydantic v2 Models

Generate Python Pydantic BaseModel classes from JSON with type annotations and Field aliases.

JSON to Python Pydantic (v2) Generator

Convert JSON payloads into strict Python Pydantic v2 BaseModel classes with type annotations.

JSON Input

Root Pydantic Model Name

Generated Python Pydantic v2 Models

from typing import Any, Optional
from pydantic import BaseModel, Field


class UserModel(BaseModel):
    user_id: str = Field(alias="userId")
    username: str
    email: str
    is_active: bool = Field(alias="isActive")
    account_balance: float = Field(alias="accountBalance")
    tags: list[str]
    company_details: CompanyDetails = Field(alias="companyDetails")


class CompanyDetails(BaseModel):
    company_name: str = Field(alias="companyName")
    employee_count: int = Field(alias="employeeCount")

About This Tool

JSON to Python Pydantic Generator converts JSON objects into modern Pydantic v2 BaseModel classes, configuring type hints, field aliases, and optional types for FastAPI and data validation.

Key Features

Generates Pydantic v2 BaseModel classes

Automatic snake_case conversion with Field(alias=...) support

Supports nested models, lists, and optional fields

How to Use This Tool

Paste your JSON payload into the input area.
Provide a root Pydantic model name.
Copy the generated Python code.

Why Use This Tool

Indispensable for FastAPI, LangChain, and modern Python 3.10+ data pipelines.
Creates nested models with proper snake_case aliases and type hints.

Pro Tips

Use model_validate_json() in Pydantic v2 to parse JSON strings directly into these models

Frequently Asked Questions

Is the output compatible with Pydantic v2?

Yes, generated models use standard Python type annotations (list[str], Optional[Any]) and Pydantic v2 Field(alias="...") syntax.

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