LangChain Has a Free Python Framework for Building Apps Powered by LLMs

LangChain is the most popular framework for building LLM-powered applications. It connects LLMs to your data, APIs, and tools.

What You Get for Free

• Chains — compose LLM calls with logic
• Agents — LLMs that use tools autonomously
• RAG — retrieval-augmented generation
• Memory — conversation history
• 50+ LLM providers — OpenAI, Anthropic, local models
• 100+ integrations — vector stores, loaders, tools

RAG Pipeline

from langchain_openai import ChatOpenAI, OpenAIEmbeddings
from langchain_community.vectorstores import Chroma
from langchain.chains import RetrievalQA

llm = ChatOpenAI(model='gpt-4')
db = Chroma.from_documents(docs, OpenAIEmbeddings())
qa = RetrievalQA.from_chain_type(llm=llm, retriever=db.as_retriever())
result = qa.invoke('What is our refund policy?')

LangChain vs LlamaIndex

Feature	LangChain	LlamaIndex
Focus	General LLM apps	Data/RAG
Agents	Full framework	Data agents
Flexibility	Higher	More opinionated

---

Need LLM app development? Check my work on GitHub or email [e-mail] for consulting.