💱 Currency Exchange App

A modern Flutter application for currency conversion and historical rate visualization, built as part of an internship learning project.

📸 Screenshots

Real-time currency converter with instant calculations Interactive historical charts with customizable currency pairs

📱 Overview

This comprehensive currency exchange app provides real-time currency conversion and historical rate analysis with a beautiful, intuitive interface. The app features two main sections: a converter for instant calculations and a graph view for historical trends.

✨ Features

🔄 Currency Converter

• Real-time conversion between 150+ major currencies (USD, EUR, GBP, JPY, AUD, CAD, CHF, CNY, SEK, NZD, TRY)
• Instant calculations as you type
• Currency swap function with animated button
• Bottom sheet selection for easy currency picking
• Clean, responsive design with custom input fields

📊 Historical Charts

• Interactive line charts showing currency rate evolution over time
• Customizable currency pairs - select any base and target currency
• Professional styling with gradients and smooth curves
• Smart date labeling with rotated, evenly-spaced dates
• Configurable grid for precise value reading
• Loading states during data fetching

🎨 UI/UX Design

• Bottom navigation between converter and chart views
• Custom styled components with consistent branding
• Responsive layout that adapts to different screen sizes
• Smooth animations and transitions
• Color-coded interface with purple gradient theme

🛠️ Technical Implementation

APIs Used

• RapidAPI Currency Exchange for real-time rates
• Frankfurter API for historical data (free, no API key required)

Key Dependencies

• fl_chart - Beautiful chart visualizations
• http - API communication
• google_fonts - Typography (Lato font)
• flutter_svg - Vector icons and graphics

Architecture

• StatefulWidget management for reactive UI
• Separate service layer for API calls
• Reusable widget components (input fields, selection sheets)
• Clean separation between converter and chart functionality

🔧 Code Highlights

Smart Data Handling

• Null-safe API response parsing
• Error handling for failed requests
• Loading states during data fetching
• Dynamic currency list management

Chart Customization

• Configurable grid intervals for optimal readability
• Intelligent date spacing (every 2-4 dates depending on range)
• Custom title widgets with proper formatting
• Responsive aspect ratios and padding

Reusable Components

• CurrencySelectionSheet - Modal bottom sheet for currency picking
• AmountInputField & ResultField - Custom styled input components
• Shared styling and theming across components

📚 Learning Outcomes

This project served as a comprehensive introduction to Flutter development, covering:

• Flutter fundamentals - Widgets, state management, navigation
• API integration - HTTP requests, JSON parsing, error handling
• Custom UI components - Building reusable, styled widgets
• Chart implementation - Data visualization with fl_chart
• Responsive design - Creating layouts that work on various screen sizes
• Dart language - Syntax, null safety, async programming

🚀 Getting Started

Prerequisites

• Flutter SDK (3.7.2+)
• Dart SDK
• Android Studio / VS Code
• API key for RapidAPI (currency conversion service)

Installation

1. Clone the repository

   git clone [repository-url]
   cd my_flutter_currency_app

2. Install dependencies

   flutter pub get

3. Add API credentials Create lib/secrets.dart:

   const String apiKey = 'your_rapidapi_key_here';

4. Run the application

   flutter run

🎯 Future Enhancements

• Add more currency pairs and exotic currencies
• Implement offline caching for better performance
• Add currency rate alerts and notifications
• Include more chart types (candlestick, volume indicators)
• Add dark/light theme toggle
• Implement currency rate predictions

👨‍💻 Development Notes

This project was developed as part of an internship learning experience to master Flutter and Dart. The focus was on creating a production-ready app with clean code, proper architecture, and professional UI/UX design.

Key Learning Areas:

• Modern Flutter development practices
• API integration and data management
• Custom widget creation and styling
• Chart libraries and data visualization
• Responsive design principles