Earlier this month I shipped PayBrackets , a free calculator that tells Americans what they actually keep from their paycheck after federal tax, state tax, and Social Security take their cut. It covers all 50 states plus D.C., it has no database, no backend, no APIs, and my total running cost is the domain. I want to walk through how it's built, because the interesting part isn't the code. It's how much you can get out of very little code if the data underneath is right. Why a ta...