n8n Workflow: OCR Invoice Extraction + Gmail Payment Reminders

OCR Invoice Extraction + Gmail Payment Reminders—Automatically

This n8n workflow watches a Google Drive folder for new invoice/receipt images, extracts key fields using Mistral AI OCR, stores them in Google Sheets, and sends scheduled Gmail payment reminders when document dates are 7, 3, 1, or 0 days away.

What this workflow does

• Monitors your Google Drive folder: Triggers when a new file is created in a specified Drive location.
• Runs OCR with Mistral AI: Downloads the new file and sends it to Mistral AI to extract OCR text from the image.
• Extracts structured invoice data: Uses a Groq-hosted LLM chain to parse the OCR text into JSON fields including:
  • Document date
  • Total amount
  • Company name
• Writes to Google Sheets (upsert by Drive file ID): Formats the extracted values, adds the Drive file ID and link, then upserts the record into Google Sheets keyed by the Drive file ID.
• Sends reminders on a daily schedule: Each day, it reads rows from the same Google Sheets document, filters entries where the document date is exactly 7, 3, 1, or 0 days from today, and emails a payment reminder via Gmail for each matching row.

Use cases

• Accounts teams who receive invoices as images and need automatic due-date follow-ups.
• SaaS operators tracking payments without manually transcribing invoice totals and dates.
• Automation engineers building reliable document-to-sheet pipelines with scheduled email reminders.

Technical details

• Google Drive trigger for new files
• Mistral AI OCR for image text extraction
• Groq Chat LLM to transform OCR text into JSON
• Google Sheets to upsert by Drive file ID (columns include ID, Document_date, Total_Note, Company_Name, Note_Link)
• Filter to select rows with dates 7/3/1/0 days away
• Gmail to send reminders (configured via a [ReceiverEmail] placeholder)