Feature-first vs layer-first folder structure — which is better for a Flutter project?
Short Answer
Layer-first (grouping by technical layer) works fine for small apps; feature-first (grouping by feature, each containing its own presentation/domain/data) scales much better as an app grows, since related code stays together.
A layer-first structure (lib/widgets/, lib/repositories/, lib/models/) means working on a single feature requires jumping between many top-level folders, and it gets harder to see what belongs together as the app grows.
A feature-first structure (lib/features/auth/{presentation,domain,data}, lib/features/profile/{...}) keeps everything related to one feature co-located, making it easier to understand, test, and even delete a feature cleanly. Most teams combine both: feature-first at the top level, with each feature internally following Clean Architecture's layer separation.
Common Mistakes
- ×Sticking with pure layer-first as an app grows past a handful of screens, making navigation and onboarding progressively harder.
- ×Going fully feature-first without shared/core folders for genuinely cross-cutting code, causing duplication across features.