🧾 Voice-Activated Expense Tracker

A voice-driven expense tracker that allows users to call a phone number, speak their expenses naturally, and have them automatically logged to their personal Google Sheet.

Built for the Vapi Build Challenge 🛠️ using:

• Vapi for voice assistant and phone interface
• Flask (Python) for backend
• Google Sheets API for expense storage

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📞 How It Works

1. The user calls the Vapi-assigned number.
2. The voice assistant (powered by Vapi) asks for expense details like:
   • "How much did you spend?"
   • "What was it for?"
   • "When did this happen?"
3. Once the user responds, the assistant sends structured data to the Flask backend.
4. The backend:
   • Creates a new sheet for first-time users
   • Logs expenses for existing users
   • Allows editing, summarizing, budgeting, and deletion

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🔧 Features

✅ Log expenses via voice
✅ Auto-create a Google Sheet per user
✅ Track monthly expenses by category
✅ Edit or delete expenses
✅ Summarize totals and budgets via voice
✅ SMS confirmation via Twilio (optional)

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🛠️ Tech Stack

Layer	Tech
Voice Assistant	Vapi
Backend	Flask (Python)
Storage	Google Sheets API
Auth	Google Cloud Service Account

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📂 Folder Structure

📁 voice-expense-tracker/
├── app.py                   # Main Flask server
├── utils.py                 # Google Sheets helper functions
├── credentials.json         # Google service account creds
├── requirements.txt         # Python dependencies
└── README.md

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🔐 Setup Instructions

1. Clone the Repo

git clone https://github.com/yourusername/voice-expense-tracker.git
cd voice-expense-tracker

2. Create a Google Cloud Project

• Enable Google Sheets API
• Create a Service Account and download credentials.json
• Share your target spreadsheet with the service account email

3. Install Dependencies

pip install -r requirements.txt

4. Run Flask App

python app.py

The server runs at http://localhost:5000

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🔌 API Endpoints

Method	Route	Description
POST	/log-expense	Logs a new expense
POST	/edit-expense	Edits an existing expense entry
POST	/delete-expense	Deletes an expense
POST	/set-budget	Sets budget
POST	/get-expenses	Fetches all expenses for a user
POST	/summary	Returns monthly/overall summary
POST	/budget	Returns remaining budget by month

All endpoints accept and return JSON.

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🗣️ Vapi Assistant Configuration

Tool: log_expense

{
  "name": "log_expense",
  "description": "Log an expense to the backend",
  "parameters": {
    "type": "object",
    "properties": {
      "name": { "type": "string" },
      "category": { "type": "string" },
      "amount": { "type": "number" },
      "date": { "type": "string" }
    },
    "required": ["category", "amount", "date"]
  }
}

Repeat similarly for edit_expense, delete_expense, etc.

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🚀 Example Voice Flow

User: "Hey, I spent 300 rupees on groceries yesterday."

Assistant:

"Got it! Logging ₹300 for groceries on May 27. Anything else you'd like to add?"

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🧪 Sample Request

POST /log-expense

{
  "name": "Aditya",
  "category": "Food",
  "amount": 500,
  "date": "2025-05-28"
}

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✨ Credits

Built by Aditya for the Vapi Build Challenge 2025 Inspired by the idea of natural, zero-friction expense tracking using voice and LLMs

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📜 License

MIT License – feel free to fork, extend, and deploy.