Pydantic

Founded by Samuel Colvin in 2022

A Python-based library for defining and enforcing structured data schemas, ideal for developers needing reliable validation and parsing.

Cost

Free

Rating

★ People love it

Time to value

Quick Setup (< 1 hour)

You can use Pydantic for defining clear data models in Python, validating input, and serializing output with minimal boilerplate. It’s built on Python type hints and runs fast due to Rust‑backed core logic. Use it when handling API payloads, configuration values, complex nested JSON, or building agents with generative AI. Popular in web frameworks like FastAPI and AI tooling, it's a go‑to for ensuring data integrity and predictable behavior.

What Pydantic does

Define and validate JSON schemas with Python classesEnforce runtime type checking for input dataCoerce or strictly validate field valuesSerialize models to JSON and dict outputIntegrate with FastAPI or other frameworks for API data validationManage application settings and configuration via typed modelsRich runtime validation and coercion using Python type hintsExceptional speed via Rust‑based coreJSON Schema generation and serialization supportCustom validator support and strict/lax mode controlSeamless integration with popular frameworks like FastAPIExtended agent framework support via Pydantic AI