💸 AI Expense Tracker — n8n + Google Drive + Sheets

Automatically extract and organize expenses from bank statements (PDFs/images) into Google Sheets using AI, n8n, and a modern web interface. One-command Docker setup.

📘 Introduction

AI Expense Tracker is a low-code automation built with n8n that leverages OpenAI, Google Drive, and Google Sheets to automate personal finance tracking.

Two ways to use it:

• 🌐 Web App – Upload receipts and bank statements (PDFs or images) via a simple Next.js interface
• 📁 Google Drive – Drop files into a folder and let automation handle the rest

Just upload your bank statement PDF or receipt image, and the workflow will:

1. Extract the data using AI (supports PDFs and images).
2. Categorize each expense intelligently.
3. Append the results to a structured Google Sheet dashboard.

Inspired by "El Hombre Más Rico de Babilonia" and "La Bolsa o la Vida", this project promotes financial awareness and digital independence through automation.

✨ Key Features

• 🐳 Docker Support – One-command setup with Docker Compose. Works on any machine.
• 🌐 Web App Interface – Upload receipts and bank statements via a simple web UI (supports PDFs and images).
• Google Drive Integration – Drop your bank statement PDFs into a folder, and the system takes it from there.
• AI-Powered Parsing – Uses GPT-4o to read and structure your expenses into JSON.
• Categorization Agent – Classifies expenses into fixed categories (Supermarket, Gastronomy, etc.).
• Automatic Google Sheets Sync – Generates a new "Expenses {Month}" tab and appends all transactions.
• Open Source – Fully local, no external servers, and zero maintenance cost.

🚀 Quick Start (Docker - Recommended)

The easiest way to get started is with Docker Compose. This will set up both the n8n automation engine and the web app in one command.

Prerequisites

• Docker and Docker Compose installed.
• A Google Cloud Project with:
  • Google Drive API enabled.
  • Google Sheets API enabled.
• A Google Sheet based on the provided template (/templates/balance.xlsx).

Steps

1. Clone the repository

   git clone https://github.com/matiasvallejosdev/ai-expense-tracker-n8n.git
   cd ai-expense-tracker-n8n

2. Configure environment variables

   cp .env.example .env

   Edit .env and add your Google Sheets dashboard URL:

   NEXT_PUBLIC_DASHBOARD_URL=https://docs.google.com/spreadsheets/d/YOUR_SPREADSHEET_ID/edit

3. Create the n8n volume

   docker volume create n8n_data

4. Start all services

   docker-compose up -d

5. Access the applications

   • Web App: http://localhost:3000 (Upload PDFs and images of receipts/statements)
   • n8n Dashboard: http://localhost:5678 (Configure workflows and credentials)

6. Configure n8n credentials

   • Go to http://localhost:5678
   • Import the workflow from /n8n/ai-expense-tracker-n8n.json
   • Set up Google Drive OAuth2 and Google Sheets OAuth2 credentials
   • Use the redirect URI: http://localhost:5678/rest/oauth2-credential/callback

7. Upload your first expense

   • Go to http://localhost:3000
   • Upload a bank statement PDF or receipt image (JPG, PNG)
   • Watch it automatically appear in your Google Sheet!

📖 Need help with Docker? Check out the Docker Guide for detailed explanations.

Managing Your Docker Application

# Stop all services
docker-compose down

# View logs
docker-compose logs -f

# View logs for specific service
docker-compose logs -f web-app
docker-compose logs -f n8n

# Restart services
docker-compose restart

# Rebuild and restart (after code changes)
docker-compose up --build -d

# Stop and remove everything (including volumes - ⚠️ deletes n8n data)
docker-compose down -v

⚙️ Alternative Setup (Manual n8n)

If you prefer to run n8n manually without Docker:

Prerequisites

• n8n installed locally.
• A Google Cloud Project with:
  • Google Drive API enabled.
  • Google Sheets API enabled.
• A Google Sheet based on the provided template (/templates/balance.xlsx).

Steps

1. Clone the repository

   git clone https://github.com/matiasvallejosdev/ai-expense-tracker-n8n.git
   cd ai-expense-tracker-n8n

2. Import the workflow
   • Go to your local n8n dashboard.
   • Import /n8n/ai-expense-tracker-n8n.json.
3. Configure credentials
   • In n8n → Credentials, create:
     • Google Drive OAuth2
     • Google Sheets OAuth2
   • Use the redirect URI:

     http://localhost:5678/rest/oauth2-credential/callback

   • Follow Google’s guide for OAuth setup: Create OAuth Client ID
4. Connect your template
   • Upload the provided /templates/balance.xlsx to your Google Drive.
   • Rename it if you wish, but keep a tab named “Expenses Model”.
5. Set your folder trigger
   • In the workflow, edit the node Google Drive Trigger and replace the folder ID with your own.
6. Run it
   • Upload a PDF statement into that folder.
   • Watch your Google Sheet auto-populate with parsed transactions!

🗂️ Google Drive Folder (Input)

This is where you should upload your bank statement PDFs. 📁 Open the Drive Folder

Each file you drop there (e.g. statement_visa.pdf) will trigger the workflow and automatically process it.

📊 Google Sheets Template (Output)

All categorized data will be appended automatically to this Google Sheets template: 📈 Open the Google Sheets Template

Or click Make a Copy to create your own editable version.

🧩 Detailed Setup (Developers)

Tech Stack

Backend (n8n Workflow)

• n8n workflow automation
• OpenAI GPT-4o for text extraction and categorization
• Google Drive API
• Google Sheets API

Frontend (Web App)

• Next.js 16 (React 19)
• TypeScript
• Tailwind CSS 4
• Shadcn/ui components
• React Hook Form + Zod validation
• Docker multi-stage builds

Customization

1. Customize Agents

   • AI Agent → parses raw text from PDF/image.
   • AI Agent – Structure Data → converts it into a valid JSON array.

2. Processing Flow

   • Web Upload/Google Drive Trigger → Download File → Extract Text (OCR for images) → AI Parse → JSON Normalize → Filter Transactions → Append to Sheet.

3. Script Filters

   • Automatically ignores tax lines (IVA, Percepciones, Impuesto de Sellos, etc.) and USD duplicates.

4. Web App Development

   cd web-app
   npm install
   npm run dev

   The app will be available at http://localhost:3000

5. Output Schema | Field | Type | Description | | ---------------- | ------ | ------------------------------------- | | Month | string | Month extracted from transaction date | | Date | string | ISO date (YYYY-MM-DD) | | Concept | string | Transaction detail | | Payment_Method | string | Credit Card / Debit Card / Cash | | Category | string | Expense category | | Amount | number | Value of transaction | | Currency | string | ARS / USD |

📊 Data Model

Fixed Taxonomy

You can extend these categories directly in the AI prompts or in the Google Sheet data validation lists.

🤖 Architecture Overview

Input Methods

Option 1: Web App (Next.js)

1. User uploads file via web interface (http://localhost:3000)
2. File sent to n8n webhook endpoint
3. n8n processes the file

Option 2: Google Drive Trigger

1. User drops file in Google Drive folder
2. n8n watches folder and detects new files
3. n8n downloads and processes the file

Processing Pipeline (Both Methods)

1. File Input → Web upload or Google Drive trigger
2. Extract File Data → Converts PDF/image to text using OCR and AI
3. Data Parser & Cleaner → Formats the raw text
4. AI Agent (GPT-4o) → Extracts transactions from text
5. AI Agent – Structure Data → Converts to JSON array
6. Parse JSON Output → Validates structure
7. Aggregate → Duplicate Sheet → Append to Sheet → Final output in your balance template

Everything runs locally on your machine through Docker — your data stays 100% private.

Docker Services

• n8n (port 5678) – Workflow automation engine
• web-app (port 3000) – Next.js frontend for file uploads

Both services communicate over a Docker bridge network.

💡 Usage

Using the Web App (Recommended)

1. Open the web interface at http://localhost:3000
2. Upload your expense document:
   • ✅ Bank statement PDFs
   • ✅ Receipt images (JPG, PNG)
   • ✅ Ticket photos from your phone
3. Wait for AI processing (usually 5-10 seconds)
4. Check your Google Sheet – new transactions appear automatically!

Using Google Drive Trigger (Alternative)

• Upload PDF → Wait for execution → Open your Google Sheet.

• The system auto-creates a new sheet for each month:

  Expenses Oct 2025

• Filter, analyze, or connect to dashboards.

• Works perfectly with the included balance template dashboard.

🤝 Contributing

Contributions are welcome! If you want to improve parsing logic, add new categories, optimize the workflow, or enhance the web app:

1. Fork the repository.
2. Create a feature branch.
3. Make your changes:
   • n8n workflows: Edit JSON files in /n8n/
   • Web app: Edit files in /web-app/
   • Docker setup: Update docker-compose.yml or Dockerfile
4. Test your changes with Docker:

   docker-compose up --build

5. Commit and push your changes.
6. Open a Pull Request.

Guidelines:

• Include a redacted PDF/image example if your update changes extraction logic
• Test both input methods (web app and Google Drive) if modifying the processing pipeline
• Update the README if you add new features or change setup steps

📞 Contact

If you have questions, suggestions, or want to collaborate:

• Name: Matías Vallejos
• 🌐 matiasvallejos.com
• 𝕏 @mativallejosdev

📄 License

This project is open source and available under the MIT License.

🧠 Inspiration

“Control your money, or your money will control you.” — La Bolsa o la Vida

“Start thy purse to fattening.” — El Hombre Más Rico de Babilonia