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12 tools · editorial

Best AI agent frameworks

Libraries and hosted runners for tool-calling agents, workflows, and multi-step jobs.

SDefault

Nothing in this tier.

AStrong
89Vercel AI SDKTypeScript apps that need streaming chat or a small tool-calling agent.Free84LangGraphAgents that need explicit steps, branches, and human approval.Free84MastraTypeScript teams who want agents, workflows, and evals in one library.Free84OpenAI Agents SDKAgents that should stay close to OpenAI’s tools, handoffs, and tracing.Free83LangChainApplication code that needs tools, retrieval, and a large example ecosystem.Free81DifyTeams who want a visual LLM app builder they can self-host.Freemium81Pydantic AIPython services that want typed tool-calling agents.Free80CrewAIRole-based multi-agent demos and workflows you want to read as a crew.Freemium80LlamaIndexDocument Q&A and agents that have to cite your own files.Free80n8nAutomations that mix model steps with the SaaS tools you already use.Freemium
BSolid
73AutoGenEngineers who want a free multi-agent library and will write the glue.Free72Semantic Kernel.NET teams adding tool-calling agents inside an existing Microsoft codebase.Free
CSituational

Nothing in this tier.

Head-to-heads

LangChain vs LlamaIndex

LangGraph vs CrewAI

Questions

Which agent framework should you build on?

Vercel AI SDK is the top-ranked pick at 89. TypeScript apps that need streaming chat or a small tool-calling agent. The score is editorial, not a measured benchmark.

Which Agents & frameworks tools are free to start?

Vercel AI SDK (free), LangGraph (free), Mastra (free), OpenAI Agents SDK (free), LangChain (free), Dify (freemium). Dollar prices say “check site” unless the software itself costs nothing to run. Confirm the current plan before you commit.

How does this ranking work?

Capability is 40% of the score, ease 25%, value 20%, and momentum 15%. S is 90 and above, A is 80 to 89, B is 70 to 79, and C is under 70. A sponsored label, if you see one, does not change the number.