LINE AI Assistant Workflow: Gemini + Gmail + Sheets (n8n)

Turn LINE messages into AI-powered actions across Gmail, Calendar, Tasks, and Sheets

This n8n workflow lets you send a LINE text (or voice note) and have a Gemini + OpenAI assistant carry out real work—reading/sending Gmail, creating Google Calendar events, managing Google Tasks, recording expenses to Google Sheets—and then replying back to you in LINE with a short Traditional Chinese response.

What this workflow does

• Receives messages via a webhook trigger: Incoming LINE text or audio is processed automatically in n8n.
• Handles voice messages with OpenAI: If the message is an audio clip, the workflow downloads the audio from the LINE Messaging API and transcribes it using OpenAI.
• Understands intent with Google Gemini: The transcribed text (or original LINE text) is sent to a Google Gemini Chat Model agent with instructions to act as a personal assistant and record expenses when requested.
• Uses Gmail tools on request: The agent can read messages or send emails using Gmail capabilities.
• Manages schedule and follow-ups: When requested, it creates events in Google Calendar and creates, lists, or deletes tasks in Google Tasks.
• Logs expenses to Google Sheets: When an expense is mentioned, it appends a new row to a target Google Sheets ledger (date, type, amount, category, description, payment method).
• Replies back in LINE: The final assistant response is sent to the original LINE conversation in short Traditional Chinese.

Use cases

• Message your expenses from LINE and maintain an always-up-to-date Google Sheets ledger.
• Ask the assistant to schedule something in Google Calendar while you’re chatting.
• Turn quick reminders into Google Tasks—create, list, or remove on demand.
• Draft or send emails via Gmail using natural language in LINE.

Technical details

• Workflow trigger: LINE webhook receiver
• AI components: n8nn8n-nodes-langchainagent with Google Gemini Chat Model + n8nn8n-nodes-langchainopen ai for audio transcription
• Google tools: gmail tool, Google Calendar, Google Tasks tool, and Google Sheets
• Utilities: HTTP Request, IF node, and integration via HTTP + LINE Messaging API audio download