LangChain Has a Free API — Build AI Apps With Any LLM in Minutes

LangChain: The Framework for LLM-Powered Applications LangChain is the most popular framework for building applications with large language models. Chain prompts, connect to databases, build RAG pipelines, create agents — all with a unified API that works with OpenAI, Anthropic, Ollama, and 50+ providers. Why LangChain Provider-agnostic — swap LLMs without changing code Chains — compose multiple LLM calls into workflows RAG — built-in document loaders, splitters, vector stores Agents — LLMs that use tools (search, code execution, APIs) Memory — conversational context across messages The Free API (Python) Basic Chat from langchain_openai import ChatOpenAI from langchain_core.messages import HumanMessage # Works with OpenAI, Ollama, Anthropic, etc. llm = ChatOpenAI ( model = " gpt-4o " , temperature = 0 ) response = llm . invoke ([ HumanMessage ( content = " Explain Kubernetes " )]) print ( response . content ) # Switch to local model (zero code changes) from langchain_ollama import Chat