We’ve all been there, one moment you were enjoying writing a shiny greenfield application, and the next, without noticing it turns into a system that is a nightmare to ship. In this talk I'll answer how we get there.

Its a 4-year journey through the design evolution of a product I’ve been working on from its inception - Wix Bookings. Today, a complex application used by millions, that scaled both its team and its codebase within this period.

I'll discuss design problems such as like code-sharing practices (aka why “commons” are evil), API-first thinking in UI components, the importance of domain modeling and boundaries, how over-testing can be damaging and ponder about decision-making.