Agent frameworks · ranked 04
Pydantic AI
Python agent framework from the Pydantic team, typed end to end.
Best for Typed Python agents
Pydantic AI is an open-source Python library for building agents with typed inputs, outputs, and tools. It comes from the team behind Pydantic. Use it when the service is Python and you want the type checker involved. Use Mastra or the AI SDK when the service is TypeScript.
Best use cases
- Python backends that call tools
- Structured outputs you want validated
- A smaller surface than LangChain
Pros
- + Open source
- + Types are the point, which keeps tool I/O honest
- + From the Pydantic team, so it matches a stack many Python APIs already use
Cons
- − Python-only, so it is the wrong pick for a Next.js UI
- − You still design the tools and pay for the model
Pricing
Open source and free. Model fees are separate. Rates: check site.
Alternatives
Agent frameworks
8.0
Mastra
TypeScript framework for agents, workflows, and evals.
Best for TypeScript agents you keep in your repo
Agent frameworks
7.3
LangGraph
Graph-shaped agents with state, from the LangChain team.
Best for Agents that are workflows, not a single loop
Agent frameworks
6.7
LangChain
The original LLM application framework, plus a hosted LangSmith side.
Best for A general LLM app framework with a huge ecosystem