Currency_Converter

Currency Converter

Description

A real-time currency converter that uses the Fixer.io API to fetch current exchange rates and convert between 170+ world currencies. Features an interactive command-line interface with support for all major currencies.

Features

• Real-time exchange rates from Fixer.io API
• Support for 170+ currencies
• Convert between any two supported currencies
• Display exchange rates
• List all available currencies
• Formatted output with thousands separators
• Error handling and validation
• Environment variable support for API key
• Interactive menu system

Stack

• Language: Python
• Libraries:
  • requests==2.28.2
• API: Fixer.io (https://fixer.io/)
• Complexity: Beginner-Intermediate

Installation

# Install dependencies
pip install -r requirements.txt

# Run the program
python main.py

API Setup

This application requires a free API key from Fixer.io:

1. Visit https://fixer.io/
2. Sign up for a free account
3. Copy your API access key
4. Use it when prompted, or set as environment variable:

Windows (PowerShell)

$env:FIXER_API_KEY="your_api_key_here"

Linux/macOS

export FIXER_API_KEY="your_api_key_here"

Permanent Setup

Add to your system environment variables or .env file.

Usage

Interactive Mode

python main.py

Example Session

==================================================
           CURRENCY CONVERTER
==================================================

Enter your Fixer.io API key: your_key_here

Fetching exchange rates...
✓ Exchange rates loaded successfully!
  Base currency: EUR
  Last updated: 2024-01-15
  Available currencies: 170

Options:
  1. Convert currency
  2. List available currencies
  3. Exit

Enter your choice (1-3): 1

------------------------------------------------------------
From currency (e.g., USD): USD
To currency (e.g., EUR): INR
Amount: 100

============================================================
           CONVERSION RESULT
============================================================
  100.00 USD = 8,350.50 INR
============================================================
  Exchange Rate: 1 USD = 83.5050 INR
============================================================

How It Works

API Integration

1. Fetches latest exchange rates from Fixer.io API
2. Base currency is EUR (Euro)
3. All rates are relative to EUR
4. API endpoint: http://data.fixer.io/api/latest?access_key={key}

Conversion Algorithm

# If converting from non-EUR currency
if from_currency != 'EUR':
    amount = amount / rates[from_currency]

# Convert to target currency
if to_currency != 'EUR':
    amount = amount * rates[to_currency]

API Response Format

{
  "success": true,
  "base": "EUR",
  "date": "2024-01-15",
  "rates": {
    "USD": 1.18,
    "GBP": 0.85,
    "INR": 88.5,
    "JPY": 130.2,
    ...
  }
}

Supported Currencies

Major Currencies

• USD - US Dollar
• EUR - Euro
• GBP - British Pound
• JPY - Japanese Yen
• CNY - Chinese Yuan
• INR - Indian Rupee
• AUD - Australian Dollar
• CAD - Canadian Dollar
• CHF - Swiss Franc
• HKD - Hong Kong Dollar

All Currencies

170+ currencies including:

• All major world currencies
• Cryptocurrencies (on some plans)
• Precious metals (Gold, Silver)
• Special Drawing Rights (SDR)

Use option 2 in the menu to see the complete list.

Class Structure

CurrencyConverter

Main class for currency conversion operations.

Methods:

• __init__(url): Initialize and fetch exchange rates
• convert(from_currency, to_currency, amount): Perform conversion
• display_conversion(...): Format and display results
• list_currencies(): Show all available currencies

Key Functions

get_api_key()

• Checks environment variable FIXER_API_KEY
• Prompts user if not found
• Provides instructions for obtaining API key

main()

• Interactive menu loop
• Handles user input
• Manages conversion workflow

Error Handling

• Network connection errors
• Invalid API key
• Unsupported currencies
• Invalid amount (negative or non-numeric)
• API rate limiting
• Timeout errors

Example Conversions

USD to EUR

From: USD
To: EUR
Amount: 1000
Result: 1000.00 USD = 847.46 EUR

GBP to INR

From: GBP
To: INR
Amount: 50
Result: 50.00 GBP = 5,205.88 INR

JPY to USD

From: JPY
To: USD
Amount: 10000
Result: 10,000.00 JPY = 90.70 USD

API Limitations

Free Plan

• 100 requests per month
• Base currency: EUR only
• Monthly data updates
• No HTTPS support

Paid Plans

• More requests
• Multiple base currencies
• Real-time updates
• HTTPS support
• Historical data
• Time-series data

Customization

Change Base Currency (Paid Plans Only)

url = f"http://data.fixer.io/api/latest?access_key={api_key}&base=USD"

Add Specific Currencies Only

url = f"http://data.fixer.io/api/latest?access_key={api_key}&symbols=USD,GBP,JPY"

Cache Exchange Rates

import json
import time

# Save rates to file
with open('rates_cache.json', 'w') as f:
    json.dump({'rates': self.rates, 'timestamp': time.time()}, f)

# Load from cache if recent
with open('rates_cache.json', 'r') as f:
    cache = json.load(f)
    if time.time() - cache['timestamp'] < 3600:  # 1 hour
        self.rates = cache['rates']

Learning Outcomes

• REST API integration
• HTTP requests with requests library
• JSON data parsing
• Error handling and validation
• Class-based design
• User input handling
• Environment variables
• Data formatting and presentation

Future Enhancements

• GUI version with Tkinter
• Historical exchange rate charts
• Currency rate alerts
• Favorite currency pairs
• Batch conversions
• Export results to CSV/Excel
• Offline mode with cached rates
• Multi-currency calculator
• Currency trend analysis
• Mobile app version

Troubleshooting

"API Error: Invalid authentication credentials"

• Check your API key is correct
• Ensure no extra spaces in the key
• Verify your Fixer.io account is active

"Network error: Connection timeout"

• Check internet connection
• Try again after a few moments
• Check if Fixer.io is accessible

"Currency 'XXX' not supported"

• Verify currency code is correct (3-letter ISO code)
• Check if currency is available in your plan
• Use option 2 to see available currencies

Rate limit exceeded

• Free plan: 100 requests/month
• Wait until next month or upgrade plan
• Implement caching to reduce requests

Alternative APIs

If Fixer.io doesn't meet your needs, consider:

• ExchangeRate-API (https://exchangerate-api.com/)
• CurrencyAPI (https://currencyapi.com/)
• Open Exchange Rates (https://openexchangerates.org/)
• Currency Layer (https://currencylayer.com/)

License

This project is open source and available for educational purposes.

Disclaimer

Exchange rates are provided by Fixer.io and may not reflect real-time market rates. This tool is for informational purposes only and should not be used for financial decisions without verification.