Pydantic Has a Free API — Data Validation That Makes Python Type-Safe

Pydantic: Data Validation Using Python Type Hints Pydantic is the most downloaded Python validation library. Define data models with type hints, Pydantic validates at runtime. Used by FastAPI, LangChain, Airflow, and thousands of production apps. Why Pydantic Define models with standard Python type hints Automatic validation and coercion JSON Schema generation Serialization/deserialization 50x faster than V1 (written in Rust) The Free API from pydantic import BaseModel , Field , EmailStr from datetime import datetime class User ( BaseModel ): name : str = Field ( min_length = 2 , max_length = 50 ) email : EmailStr age : int = Field ( ge = 0 , le = 150 ) created_at : datetime = Field ( default_factory = datetime . now ) tags : list [ str ] = [] # Valid user = User ( name = " Alice " , email = " alice@example.com " , age = 30 ) print ( user . model_dump ()) # Dict print ( user . model_dump_json ()) # JSON string # Invalid — raises ValidationError try : User ( name = " A " , email = " not