LangChain
Most-adopted framework for chaining LLM calls, tools, and agents. Python and JS/TS.
- License
- MIT
- Install
- pip package
- Website
- https://www.langchain.com
- GitHub
- https://github.com/langchain-ai/langchain
pip install langchain
PydanticAI
Type-safe Python agent framework from the Pydantic team; MCP-native tool integration.
- License
- MIT
- Install
- pip package
- Website
- https://ai.pydantic.dev
- GitHub
- https://github.com/pydantic/pydantic-ai
pip install pydantic-ai
When to reach for which
LangChain — Most-adopted framework for chaining LLM calls, tools, and agents. Python and JS/TS.
PydanticAI — Type-safe Python agent framework from the Pydantic team; MCP-native tool integration.
Both sit in the Agent Frameworks category — they're substitutes, not complements. Pick by your install constraint (MCP-native, license, hosting model) and which tag overlap matters most to your stack.