Day 85 of #100DaysOfCode — Building a Mini Flask App: Expense Tracker

Flask learning is done. Today I built a complete mini Flask application from scratch: an expense tracker where users can register, log in, add expenses, filter them by category, and see a running total. Everything from days 78 to 84 came together in one day of building. Here's how it's architected and how it works. Why an Expense Tracker I wanted something small enough to finish in a day but real enough to actually use. An expense tracker hits that balance, it solves a genuine problem, it uses e