In this video I build a full Facebook Messenger AI chatbot end-to-end inside n8n—no third-party chatbot tools, just the real Meta setup + a clean n8n workflow. I start by creating a Meta app (Business type), then I walk you through the Messenger API setup: adding a webhook callback URL, setting a verify token, and fixing the common “couldn’t be validated” error by returning the hub.challenge back to Meta. Once that handshake is done, I subscribe to the “messages” webhook event, connect a Facebook Page, and generate the Page access token (keep that token safe—Meta only shows it once). Then we jump into n8n: webhook node (GET + POST), IF node to validate hub.mode and hub.verify_token, Respond to Webhook for the challenge, and finally the AI agent. I pass the incoming Messenger text into an n8n AI Agent (I use OpenAI as the brain), then send the agent’s reply back to Messenger using an HTTP Request node with the correct Graph API URL, headers, and JSON body. At the end, I switch from test to production webhook URL, take the Meta app live (privacy policy URL required), and I show the “missing memory” problem—then fix it by adding simple memory keyed by the sender ID so the bot can remember context across messages.