Pydantic

Pydantic builds tools for developers to validate application data, build AI agents and monitor production software. Its open-source Pydantic Validation library checks and serializes data using Python type annotations, while Pydantic AI provides an agent framework and Pydantic Evals supports code-based evaluations. Logfire brings traces, logs and metrics together through OpenTelemetry, helping teams inspect agent behavior and improve applications. Logfire AI Gateway adds model routing and spending controls.

Founder and CEO Samuel Colvin started the Python library in 2017 and established the commercial company in 2022. Its engineering approach connects Python’s type system with a Rust validation core; models can also generate JSON Schema for integration with other tools. Pydantic extended that approach to agent code execution with Monty, an open-source Python interpreter written in Rust. Monty lets agents express loops, conditionals and asynchronous calls while restricting interaction with the outside world to functions explicitly supplied by developers.

In 2024, Logfire attracted 2,000-plus developers and 150 companies during its beta phase. Its commercial observability business launched Logfire out of beta that year, alongside a $12.5 million Series A led by Sequoia, with participation from Partech and Irregular Expression.