Build a website FAQ chatbot with n8n, Google Sheets and Gemini (no vector database)

Description and use

A lightweight FAQ chatbot for small businesses using n8n, Google Sheets and Gemini without a vector database.

Problem

Small businesses need a simple FAQ chatbot that can be updated by editing a spreadsheet, without complex embeddings or vector databases.

Outcome

A lightweight FAQ chatbot that avoids embeddings, allows instant updates via a spreadsheet, and captures leads with email/phone extraction.

Workflow

• Set up n8n Chat Trigger (public, webhook, response mode "When Last Node Finishes")
• Embed chat widget on website with CDN CSS/JS
• Read FAQ tab from Google Sheets
• Build knowledge base string from active rows, capped at 15,000 characters
• Detect email/phone in user message with regex
• Send prompt to Gemini AI Agent with system message containing business details and knowledge base
• Log conversation to Chat log sheet
• If contact details present, append or update Leads sheet
• Return reply text to widget

Evidence

For a plumber, a dental clinic or a local shop with 30 to 80 frequently asked questions, that is far more machinery than the problem needs

Source

The FAQ lives in a Google Sheet, the whole FAQ goes into the prompt on every message, and an n8n AI Agent with Gemini (free tier) answers only from it, logs every conversation and captures leads.

Source

I cap the knowledge base at 15,000 characters as a safety valve.

Source