A comprehensive guide to building layered, reusable architecture for large Next.js applications. Covers six architectural layers: App Router colocation, feature-based folder structure with barrel exports, Turborepo monorepo setup for sharing code across multiple apps, Server Components data-fetching boundaries with Server Actions for mutations, a testing strategy mapped to each layer (Vitest for units, React Testing Library for features, Playwright for E2E), and a CI/CD pipeline using Turborepo's remote caching and affected-package filtering. Includes concrete folder structures, code examples, and a complete blueprint showing how all layers compose together.
Table of contents
Table of ContentsThe Core Problem: Coupling Without IntentionLayer 1: The App Router and ColocationLayer 2: Feature-Based Folder StructureLayer 3: Monorepo with Turborepo (Sharing Logic Across Apps)Layer 4: Server Components and Data-Fetching BoundariesLayer 5: Testing Strategy for a Layered CodebaseLayer 6: CI/CD with TurborepoPutting It All Together: The Full BlueprintCommon Pitfalls and How to Avoid ThemFinal ThoughtsSort: