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Agents & frameworks · A-tier

LangChain

Open-source library for chains, tools, and retrieval. The library is free; LangSmith hosting is separate.

Open LangChainBest AI agent frameworks

Best for

Application code that needs tools, retrieval, and a large example ecosystem.

What it is

LangChain is an open-source library for composing model calls, tools, and retrieval in Python and JavaScript. The library is free. Observability and deployment sit in the paid LangSmith product. It is the default ecosystem a lot of agent tutorials still start from.

open-sourcelibraryretrievalAgents & frameworks

Score breakdown

  • Capability 40%86
  • Ease 25%70
  • Value 20%90
  • Momentum 15%84

Pricing

Free

Starting price: $0

The library is open source. LangSmith and hosted deployment are priced separately. Check LangSmith if you need the platform.

Dates

Released Oct 2022 (month precision).

Added to StackPick 14 Oct 2026.

Alternatives

A-tier · 80

LlamaIndex

Document Q&A and agents that have to cite your own files.

A-tier · 84

LangGraph

Agents that need explicit steps, branches, and human approval.

A-tier · 89

Vercel AI SDK

TypeScript apps that need streaming chat or a small tool-calling agent.

Comparisons

vs LlamaIndex

Questions

What is LangChain best for?

Application code that needs tools, retrieval, and a large example ecosystem.

How much does LangChain cost?

Free. Starting price: $0. The library is open source. LangSmith and hosted deployment are priced separately. Check LangSmith if you need the platform.

What are alternatives to LangChain?

LlamaIndex, LangGraph, Vercel AI SDK are the alternatives we file next to it. Open a comparison when one exists.