LangChain

LangChain is an open-source framework with a prebuilt agent architecture and integrations for any model or tool. Build agents and LLM-powered applications in under 10 lines of code, with integrations for OpenAI, Anthropic, Google, and hundreds more.

When to use

Use LangChain when you need to:

• Build tool-calling agents with create_agent() and a prebuilt agent loop
• Switch model providers without changing application code via init_chat_model()
• Add structured output to parse LLM responses into typed objects
• Integrate with any model or tool using LangChain's provider packages
• Use middleware for cross-cutting concerns like rate limiting and caching

When NOT to use

• For complex multi-step workflows with custom control flow, use LangGraph instead
• For a batteries-included agent with planning, subagents, and context management, use Deep Agents instead
• LangChain provides the core building blocks; LangGraph adds orchestration; Deep Agents adds high-level capabilities on top