LangChain Has a Free API — Build AI Apps with Composable Chains

#ai #python #langchain #llm

LangChain is the most popular framework for building AI-powered applications. It connects LLMs to tools, databases, and APIs with composable chains.

What Is LangChain?

LangChain provides abstractions for working with LLMs. Build RAG, agents, chatbots, and AI pipelines with reusable components.

Features:

LLM integration (OpenAI, Anthropic, Ollama, etc.)
RAG (Retrieval Augmented Generation)
Tool/function calling
Memory management
Streaming
Free and open source

Quick Start

pip install langchain langchain-openai

Python Examples

from langchain_openai import ChatOpenAI
from langchain.prompts import ChatPromptTemplate

llm = ChatOpenAI(model="gpt-4o")

# Simple chain
prompt = ChatPromptTemplate.from_template("Explain {topic} in 3 sentences")
chain = prompt | llm
result = chain.invoke({"topic": "Kubernetes"})
print(result.content)

RAG Example

from langchain_community.document_loaders import WebBaseLoader
from langchain_openai import OpenAIEmbeddings
from langchain_community.vectorstores import Chroma
from langchain.chains import RetrievalQA

# Load docs
loader = WebBaseLoader("https://docs.example.com")
docs = loader.load()

# Create vector store
vectorstore = Chroma.from_documents(docs, OpenAIEmbeddings())

# RAG chain
qa = RetrievalQA.from_chain_type(llm, retriever=vectorstore.as_retriever())
result = qa.invoke("How do I deploy?")
print(result["result"])