Process scanned invoices with Google Drive, OCR & OpenAI to Google Sheets

This template allows you to automatically process scanned invoices from Google Drive, extract key information using AI, and organize the data in Google Sheets with email notifications.

Overview

This comprehensive workflow automates the entire invoice processing pipeline by monitoring a Google Drive folder for new invoice uploads, intelligently processing both PDF and image formats, extracting structured data using AI-powered information extraction, and automatically organizing the results in a Google Sheet while sending email notifications. The system handles various file formats and includes smart fallback mechanisms for challenging documents like CamScanner PDFs.

How it Works

1. File Monitoring: The workflow continuously monitors a specified Google Drive folder for new invoice files using a trigger that checks every minute for newly created files.

2. File Processing: When new files are detected, the system downloads them and determines the file type (PDF or image) using a smart switch mechanism.

3. Text Extraction:

   • For PDFs: Attempts direct text extraction first
   • For Images: Uses OCR.Space API for optical character recognition
   • For problematic PDFs (like CamScanner): Falls back to OCR processing

4. AI Information Extraction: Processes the extracted text through OpenAI's language model to identify and extract key invoice information including:

   • Company name
   • Total amount
   • Currency
   • Invoice date
   • Invoice number

5. Data Storage: Automatically appends the extracted information to a Google Sheet with links back to the original scanned documents.

6. Notification: Sends formatted email notifications via Mailgun when new invoices are processed, including an HTML table summary.

How to Use

1. Setup Google Drive: Create a dedicated folder in Google Drive for invoice uploads and note the folder ID.

2. Configure Credentials: Set up the following credential connections in n8n:

   • Google Drive OAuth2 API
   • Google Sheets OAuth2 API
   • OpenAI API
   • OCR.Space API
   • Mailgun API

3. Update Configuration:

   • Replace the Google Drive folder ID with your target folder
   • Replace the Google Sheets document ID with your destination spreadsheet
   • Update email addresses in the Mailgun node

4. Test the Workflow: Use the manual trigger to process existing invoices in your folder for initial testing.

5. Activate: Enable the workflow to start automatic monitoring of new invoice uploads.

Requirements

External APIs:

• OpenAI API - For AI-powered information extraction from invoice text
• OCR.Space API - For optical character recognition of image-based invoices
• Mailgun API - For sending email notifications

Google Services:

• Google Drive API - For monitoring folders and downloading files
• Google Sheets API - For storing extracted invoice data

Setup Prerequisites:

• Google Drive folder dedicated to invoice uploads
• Google Sheet with appropriate column headers (date, company name, total, currency, invoice number, scan link, etc.)
• Email domain configured with Mailgun (or alternative email service)
• OCR.Space account for image processing capabilities: https://ocr.space/OCRAPI

Recommended Settings:

• Set the Google Drive trigger to check for new files every minute
• Ensure sufficient API rate limits for your expected invoice volume
• Configure proper error handling for failed OCR or AI extraction attempts