The $40K/month website that does one thing

Angus Chang built a website that does exactly one thing: convert PDF bank statements into Excel spreadsheets. In 2021, he was trying to figure out how long his savings would last after quitting his job, but his bank only provided PDF statements. He wrote code to extract the transaction data, realized it was harder than expected, and figured other people must have the same problem. Today, that single-purpose website makes $40,000 per month in revenue, and Chang runs it entirely alone—no employees, no co-founders, no outside funding.

Finding and validating the idea

Chang didn't search for a business idea. He encountered a personal pain point and built a solution for himself first. The key insight: the problem was hard enough that he struggled to solve it with code, which signaled that other people would pay for a ready-made solution. He and a friend built an MVP in about a week—a Kotlin backend with a Next.js frontend—and immediately started running Google search ads to see if anyone would use it. People uploaded bank statements right away. That was his validation.