Build a RAG Chatbot with Next.js in 2026

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RAG Retrieval-Augmented Generation is the technique behind every custo

This tutorial walks you through building a RAG chatbot with Next.js, OpenAI, and a vector database from scratch.

What is RAG?

Regular ChatGPT only knows what it was trained on. RAG fixes this by:

Prerequisites

- Node.js 18+ - Basic React/Next.js knowledge - OpenAI API key - Neon or Supabase account (for PostgreSQL + pgvector)

Step 1: Project Setup

Create a new Next.js app:

Step 2: Database Schema

Create a table to store document chunks and their vector embeddings.

Step 3: Document Ingestion

Before your chatbot can answer questions, you need to ingest your documents into the vector database.

Step 4: Embedding Generation

OpenAI's text-embedding-3-small model converts text to 1536-dimensional vectors.

Step 5: Building the Chat API

Create an API route that handles the RAG pipeline:

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Build a RAG chatbot with Next.js in 2026 - step-by-step tutorial covering embeddings, vector databases, OpenAI integrat