Why Every Developer Should Build a Personal Finance Tool (I Built KeepRule)

Three years ago, I was a full-stack developer who couldn't explain compound interest to save my life. I tracked expenses in a spreadsheet that I updated once a month (if I remembered). My "investment strategy" was whatever my coworker mentioned at lunch. Then I decided to build a personal finance tool. That single decision taught me more about software engineering, product thinking, and financial literacy than any course or book ever could. Here's why I think every developer should do the same — and what I learned building KeepRule . The Problem That Started It All I noticed something strange in my developer circle: we build sophisticated systems for billion-dollar companies, but most of us manage our own money with the financial sophistication of a college freshman. We can explain microservices architecture but not tax-loss harvesting. We can optimize database queries to save milliseconds but won't spend 30 minutes optimizing our 401(k) allocation. We understand technical debt but ign