LangChain
Agent frameworksOpen sourceOur take: The most widely used LLM framework; huge ecosystem, sometimes heavy abstractions.
Use cases: LLM apps, agents, RAG
Official site: https://www.langchain.com (link checked 2026-10-14)
Similar tools
LangGraph
Agent frameworksOpen sourceGraph-based control for agents that need reliability and state.
stateful agents · multi-agent graphs
CrewAI
Agent frameworksOpen sourceRole-based multi-agent crews; quick to start.
multi-agent teams
AutoGen
Agent frameworksOpen sourceMicrosoft's multi-agent framework; research-flavored.
multi-agent conversation
LlamaIndex
Agent frameworksOpen sourceBest known for data/RAG pipelines over your documents.
RAG · document agents
OpenAI Agents SDK
Agent frameworksOpen sourceLightweight official SDK; minimal abstractions.
agents · handoffs · tool use
Mastra
Agent frameworksOpen sourceTypeScript-first agent framework; good fit for JS builders.
TypeScript agents · workflows