When you start building Flutter apps that grow beyond a few screens, the way you organize your project files becomes crucial for maintainability and scalability. Two common approaches are the layer-based and feature-based folder structures. In a layer-based structure, you group files by their technical role, such as putting all models in one folder, all views in another, and so on. While this can work for small projects, it often leads to scattered code as your app grows, making it harder to locate all files related to a specific feature.

A feature-based folder structure organizes your code by app features instead of technical layers. Each major feature—like authentication or user profiles—gets its own top-level folder, which contains all the files needed for that feature: screens, widgets, logic, and possibly data sources. This approach keeps related files together, making it easier to find, update, and test feature-specific code. It also helps teams work independently on different features without stepping on each other's toes.

Adopting a feature-based folder structure brings several benefits, especially for large projects and teams. By grouping all files related to a feature together, you reduce the cognitive load required to understand and modify the codebase. This makes onboarding new developers easier, as they can focus on just one feature at a time. Teams can work in parallel on different features without causing merge conflicts or duplicating effort. Refactoring is safer, since changes are isolated to the relevant feature folder. Compared to layer-based organization, where files for a single feature may be scattered across the project, feature-based organization keeps everything cohesive and modular, which is essential as your app and team scale.