Python command line expense tracker application.

Features

• Add, list, and delete expenses (amount, category, description, date)
• Saves data to a JSON file
• Reports: total, average, biggest expense, breakdown by category and by month
• Sorting by amount, date, or category-then-amount
• Validation with a custom exception hierarchy

Project structure

• expense.py: the Expense model + validation
• tracker.py: ExpenseTracker: manages expenses, persistence, and reports
• main.py: interactive command-line menu
• storage.py: Storage abstract base class with JsonStorage and CsvStorage

Usage

add / list / report / delete / import / summary / quit
> add
Category: food
Amount: 12.50
Description: lunch
Added.