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LangChain

rag
Assess

LangChain is one of the most widely-adopted frameworks for building LLM-powered applications — particularly RAG pipelines (connecting LLMs to your own documents and data). However, for agent orchestration, its successor LangGraph is now recommended.

Buy vs Build

LangChain is a build framework. There is no "buy" version — it's open-source Python (and JavaScript) code you include in your application.

Why It's in Assess (Not Trial)

LangChain has 80K+ GitHub stars and remains extremely useful, but the team has been clear: use LangGraph for agents, not LangChain. The reasons:

  • LangChain's agent abstraction is verbose and hard to debug
  • LangGraph, built by the same team, provides a cleaner mental model for stateful agent workflows
  • LangChain's "chain" abstraction was designed for sequential pipelines, not the branching, looping nature of modern agents

Where LangChain is still excellent:

  • RAG pipelines — connecting LLMs to PDFs, databases, websites, and knowledge bases
  • Document Q&A — build "chat with your docs" applications quickly
  • Integration breadth — 600+ integrations with data sources, vector stores, and tools
  • LCEL (LangChain Expression Language) — declarative syntax for composing retrieval + generation pipelines

When to Use LangChain vs LangGraph

Use Case Recommended Tool
RAG / document search LangChain
Chat with your docs LangChain
Multi-step agent workflows LangGraph
Complex branching logic LangGraph

Getting Started

pip install langchain langchain-anthropic langchain-community

from langchain_anthropic import ChatAnthropic
from langchain_core.prompts import ChatPromptTemplate

chain = ChatPromptTemplate.from_template("Explain {topic} to a beginner") | ChatAnthropic(model="claude-sonnet-4-6")
result = chain.invoke({"topic": "vector databases"})

Key Characteristics

Property Value
Language Python and JavaScript/TypeScript
License MIT
Integrations 600+ data sources and tools
Provider LangChain Inc.
Website python.langchain.com
GitHub langchain-ai/langchain

Further Reading