Expense Tracker - Setup Guide

Quick Start

1. Clone the repository

git clone https://github.com/varshitverma/api-exp-tracker.git
cd backend

2. Generate & Collect API Keys (IMPORTANT - Do This First!)

Before proceeding with setup, you need to generate two API keys:

A. Supabase API Keys

1. Go to Supabase
2. Create a new project or use existing one
3. Go to Settings → API
4. Copy these values:
   • Project URL - This is your SUPABASE_URL
   • Service Role Secret - This is your SUPABASE_KEY

B. ExchangeRate API Key

1. Go to ExchangeRate-API
2. Sign up for a free account
3. Copy your API Key
4. This will be part of your EXCHANGE_RATE_API_URL

3. Create a .env file

Create a .env file in the backend directory and add your API keys:

SUPABASE_URL=your_supabase_project_url
SUPABASE_KEY=your_supabase_secret_key
EXCHANGE_RATE_API_URL=https://v6.exchangerate-api.com/v6/YOUR_EXCHANGERATE_API_KEY/latest

4. Install dependencies

pip install -r requirements.txt

5. Supabase Setup & Database Migrations

Login to Supabase

npx supabase login
# Please login with your Supabase account

Link your Supabase Project

npx supabase link
# Select the project you created on Supabase for this app

Create Migration (if not already created)

npx supabase migration new create_expenses_table

Push Migrations to Database

npx supabase db push
# This will push the migration to your Supabase project and create the expenses table in your database

Apply Migrations

npx supabase migration up

Reset Database (Optional - use if you need to start fresh)

npx supabase db reset --linked
# This will reset your database and run all migrations again
# Use this if you want to start fresh with the database in case of any issues
# Then run all commands above again to set up the database

6. Start the Server

python -m uvicorn main:app --reload

Server runs on: http://127.0.0.1:8000

7. Access API Documentation

Once the server is running, you can view interactive API documentation:

• Swagger UI (Interactive): http://127.0.0.1:8000/api/docs

  • Best for testing endpoints directly
  • Try out requests and see responses

• ReDoc (Beautiful Docs): http://127.0.0.1:8000/api/redoc

  • Clean, organized documentation
  • Great for reading API specifications

• OpenAPI Schema (JSON): http://127.0.0.1:8000/api/openapi.json

  • Raw OpenAPI specification
  • For programmatic use & third-party tools

8. Update Requirements

After installing new packages, update requirements file:

pip freeze > requirements.txt

---

API Endpoints

Add Expense

POST /expenses

{
  "amount": 50.0,
  "category": "food",
  "description": "lunch",
  "date": "2026-02-04T12:00:00",
  "payment_method": "card"
}

Get All Expenses

GET /expenses

Get Specific Expense

GET /expenses/{id}

Update Expense

PUT /expenses/{id}

{
  "amount": 75.0,
  "category": "food",
  "description": "dinner",
  "date": "2026-02-04T12:00:00",
  "payment_method": "card"
}

Response:

{
  "success": true,
  "message": "Expense updated",
  "data": {
    "id": 1,
    "amount": 75.0,
    "category": "food",
    "description": "dinner",
    "date": "2026-02-04T12:00:00",
    "payment_method": "card"
  }
}

Convert Expenses to Another Currency

GET /expenses/convert/{target_currency}

Converts all user expenses from INR to a target currency using real-time exchange rates.

Example Response:

{
  "success": true,
  "data": [
    {
      "id": 1,
      "amount": 100,
      "original_amount": 100,
      "original_currency": "INR",
      "converted_amount": 1.11,
      "target_currency": "USD",
      "category": "food",
      "description": "lunch"
    }
  ],
  "total_in_target_currency": 111.5,
  "exchange_rate": 0.0111,
  "target_currency": "USD",
  "base_currency": "INR"
}

Delete Expense

DELETE /expenses/{id}

Deletes an expense by ID.

Response:

{
  "success": true,
  "message": "Expense deleted"
}

---

3rd Party APIs

Exchange Rate API

Purpose: Convert user expenses to different currencies when traveling.

Provider: ExchangeRate-API

Setup: API key is configured in .env file (see Step 3 above)

Feature Description: When a user selects a country/currency from the UI:

1. Backend receives the target currency code (e.g., USD, EUR, GBP)
2. Backend calls the Exchange Rate API to fetch current exchange rates from INR
3. All existing expenses are converted to the selected currency
4. User sees individual expenses and total expenses in the selected currency
5. This is helpful when traveling to another country to track spending in local currency

Supported Currencies: 160+ currencies including USD, EUR, GBP, JPY, INR, AED, and more.

---

Database Schema

Column	Type	Notes
id	BIGINT	Primary Key (auto-generated)
amount	FLOAT	Expense amount
category	VARCHAR(50)	Category name
description	TEXT	Optional description
date	TIMESTAMP	When expense occurred
payment_method	VARCHAR(50)	cash, card, digital wallet
created_at	TIMESTAMP	Auto-set on creation
updated_at	TIMESTAMP	Auto-set on creation

--

Folder Structure

backend/
├── app/
│   ├── model/
│   │   └── expense_model.py
│   └── routes/
│       ├── get_routes.py
│       └── post_routes.py
├── migrations/
│   └── 001_create_expenses_table.sql
├── main.py
├── setup_db.py
├── requirements.txt
└── .env

---

📦 Deployment Guide (EC2 + Nginx + FastAPI)

This guide covers deploying your Expense Tracker backend to AWS EC2 with Nginx reverse proxy.

🚀 1️⃣ EC2 Server Setup (Ubuntu)

Step 1: Launch EC2 Instance

• OS: Ubuntu 22.04
• Instance type: t3.small (recommended minimum 2GB RAM)

Open Security Group Ports:

• 22 (SSH)
• 80 (HTTP)
• 443 (HTTPS)

Step 2: Connect via SSH

ssh -i your-key.pem ubuntu@YOUR_PUBLIC_IP

Step 3: Update Server

sudo apt update && sudo apt upgrade -y

🐍 2️⃣ Backend Deployment (FastAPI + Gunicorn)

Step 1: Clone Repository

cd ~
git clone https://github.com/your-repo/backend.git
cd backend

Step 2: Install Python & Dependencies

# Install Python and venv
sudo apt install python3 python3-venv python3-pip -y

# Create virtual environment
python3 -m venv env
source env/bin/activate

# Install dependencies
pip install -r requirements.txt
pip install gunicorn

# Deactivate when done
deactivate

Step 3: Create .env File

nano .env

Add your API keys:

SUPABASE_URL=your_supabase_project_url
SUPABASE_KEY=your_supabase_secret_key
EXCHANGE_RATE_API_URL=https://v6.exchangerate-api.com/v6/YOUR_API_KEY/latest

Save with Ctrl+X → Y → Enter

Step 4: Create systemd Service

sudo nano /etc/systemd/system/fastapi.service

Paste the following:

[Unit]
Description=FastAPI App
After=network.target

[Service]
User=ubuntu
WorkingDirectory=/home/ubuntu/backend
ExecStart=/home/ubuntu/backend/env/bin/gunicorn \
          -k uvicorn.workers.UvicornWorker \
          main:app \
          --bind 127.0.0.1:8000 \
          --workers 2
Restart=always

[Install]
WantedBy=multi-user.target

Save with Ctrl+X → Y → Enter

Step 5: Enable & Start Backend Service

sudo systemctl daemon-reload
sudo systemctl enable fastapi
sudo systemctl start fastapi

# Check status
sudo systemctl status fastapi

🌐 3️⃣ Install & Configure Nginx

Step 1: Install Nginx

sudo apt install nginx -y

Step 2: Configure Nginx

sudo nano /etc/nginx/sites-available/default

Replace with:

server {
    listen 80;
    server_name yourdomain.com www.yourdomain.com;

    location /api/ {
        proxy_pass http://127.0.0.1:8000;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
    }

    location / {
        root /var/www/html;
        index index.html;
        try_files $uri /index.html;
    }
}

Step 3: Test & Restart Nginx

# Test configuration
sudo nginx -t

# Restart Nginx
sudo systemctl restart nginx

# Enable on startup
sudo systemctl enable nginx

🔒 4️⃣ SSL Certificate (HTTPS with Let's Encrypt)

# Install Certbot
sudo apt install certbot python3-certbot-nginx -y

# Generate certificate
sudo certbot --nginx -d yourdomain.com -d www.yourdomain.com

# Auto-renewal enabled by default

✅ Verification

• API: http://yourdomain.com/api/v1/expenses
• Docs: http://yourdomain.com/api/docs
• Check logs: sudo journalctl -u fastapi -f