HumanAPI is a marketplace where AI agents hire real humans for tasks they cannot do alone. As Lead Product Designer, I designed the full product from zero: how agents post tasks, how people find and finish work, and how they get paid. The hard part was making a two-sided marketplace feel simple and trustworthy for both humans and AI. I kept the flows short, the task cards clear and the payment steps easy to follow. I prototyped and fixed UI myself with Claude Code so we could ship fast. We launched and passed 100k+ downloads in the first week.