If you've wanted to add an AI chatbot to a website but assumed it needs a paid OpenAI account, a vector database cluster, and a weekend of DevOps — this guide is for you. We'll build a customer support chatbot that answers questions only from your own documents , refuses to make things up, and deploys to a public URL. Total cost: ₹0 / $0 .

Here's the finished thing, live: try the demo — ask it about shipping, then ask it for a pizza menu and watch it politely decline to hallucinate.

What we'll use:

FastAPI — the backend (one file)

RAG (Retrieval-Augmented Generation) — a lightweight version with no vector database

Groq — free-tier LLM API, extremely fast

Vercel — free serverless hosting, deployed from your terminal

Time to complete: about 30 minutes.

Why "answers only from your documents" is the whole product

A raw LLM will cheerfully invent your refund policy. That's not a chatbot a business can use.…