Advanced
llm-apps
2h 0m
Build AI Apps with LangChain: Beginner Guide
ToolNova Team
1,563 views
03 Jul 2026
Learn to build production AI applications using LangChain, Python, and large language models.
Step-by-Step Guide
1
Install LangChain
Run: pip install langchain langchain-openai. Set your OPENAI_API_KEY environment variable.
Tip: Use python-dotenv to manage API keys securely.
2
Create a Simple Chain
Build a prompt template, connect it to an LLM, and chain them together with | operator.
Tip: Start with ChatOpenAI model and a PromptTemplate.
3
Add Memory
Use ConversationBufferMemory to give your app memory of past messages.
Tip: For long conversations, use ConversationSummaryMemory to save tokens.
4
Build a RAG System
Load documents, create embeddings, store in a vector database, and retrieve relevant context.
Tip: FAISS is free and works locally. Pinecone for production.
5
Deploy with FastAPI
Wrap your LangChain app in a FastAPI endpoint and deploy to a cloud server.
Tip: Add streaming with StreamingResponse for real-time responses.
<p>LangChain is the most popular framework for building AI-powered applications. This guide gets you from zero to a working AI app.</p>
langchain
python
llm
rag
ai-development