Pydantic — The Quiet Framework Powering Python’s Data Reliability

In 2017, British software engineer Samuel Colvin was working on projects that needed clean, validated data. He found Python’s dynamic typing great for flexibility, but terrible for reliability. So, he started building a small tool to parse and validate data using Python’s new type hints. That weekend project became Pydantic.

Pydantic let developers define classes with type annotations, and automatically validated incoming data — turning messy JSON into structured Python objects. It brought a level of safety and clarity that Python lacked, and quickly became essential for API development. Its adoption exploded when FastAPI, a modern web framework, chose Pydantic as its core data layer.

In 2023, Colvin and co-founder Adrian Garcia Badaracco formalized the project into a company. They raised $4.7 million in seed funding from Sequoia Capital and ParTech, with angel backing from developers at Stripe, Vercel, and Notion. The business model: offer performance upgrades, commercial licenses, and support for teams relying on Pydantic in production.

That same year, they launched Pydantic V2, a complete rewrite using Rust under the hood for major performance gains. The new version offered strict mode, better schema support, and faster validation — making it even more attractive for companies scaling with Python.

Today, Pydantic is downloaded over 150 million times a month, used by teams at Microsoft, Netflix, and NASA. What started as a side project became a core part of the Python ecosystem — not by trying to replace the language, but by making it more dependable.