Mini App Builder — Episode 1: I Built a Mini App on Korea's Biggest Fintech in One Day
One day. Zero lines of code written by hand. $0 cost. I built a quiz mini app and launched it on Apps in Toss — Korea's biggest fintech super app with 24.8 million monthly active users. Submitted for review, approved in two business days, went live. Ten days later, 52 people had used it. The most active age group wasn't the 20-somethings I'd designed it for. It was people in their 50s. This is that story. What This Post Covers Building and launching a price guessing quiz on Apps in Toss — what the platform is, why a price quiz made sense, how Claude Code with an MCP connection generated the entire codebase from a single prompt, and the brutally honest post-launch data. If you've been curious about mini app platforms but don't know where to start, this is a real case study with real numbers. Why a Price Quiz on Toss Apps in Toss is basically Korea's version of WeChat Mini Programs. Third-party developers build HTML/JS web apps that run directly insi...