What is JSON to Pydantic Model Generator?
This tool converts JSON data into Pydantic v2 BaseModel classes with automatic type inference. It generates modern Python 3.10+ type hints (list[T] instead of List[T]), handles nested models, Optional types, and detects ISO date strings.
How to Use
- Paste your JSON object or array into the input area
- Configure options: root class name, snake_case conversion, null handling, date detection
- Click "Generate Pydantic Models" to create the code
- Copy the output and use it in your Python project
Why Use This Tool?
Tips & Best Practices
- Use realistic sample data for accurate type inference
- Enable snake_case for idiomatic Python field names
- Field aliases allow JSON with camelCase keys to work seamlessly
- Null values are converted to Optional types (T | None)
Frequently Asked Questions
What is Pydantic?
Pydantic is a Python library for data validation using Python type annotations. It provides automatic data parsing, validation, serialization, and generates JSON schemas. It is widely used with FastAPI, Django, and other frameworks.
How are JSON types mapped to Python?
JSON strings become str, integers become int, floats become float, booleans become bool, null becomes T | None, arrays become list[T], and nested objects become separate BaseModel classes.
Why use snake_case conversion?
Python convention uses snake_case for variable and attribute names, while JSON often uses camelCase. This option converts field names and adds Field(alias="...") so the original JSON keys still work during deserialization.
Is my data sent to a server?
No, all processing happens entirely in your browser. Your JSON data never leaves your device.