What does it take to run a massive Flutter codebase with 60+ engineers, 100+ modules, and multiple apps—mobile and web? At QuintoAndar, we've spent the last couple of years scaling our Flutter monorepo to meet the demands of a fast-growing, multi-platform product suite. This talk dives deep into the real-world challenges we've faced, architectural decisions, and tooling we use to keep our developers happy and productive. We’ll cover how we organize and integrate hundreds of modular packages, sharing code between multiple of our products in format of Flutter mobile and web apps, while also improving the developer experience for both seasoned engineers and newcomers.