Next.js App Router Guide

App Router mental model

Folders define routes; layout.js wraps segments; loading.js streams skeletons; error.js isolates failures. Parallel routes and intercepting routes power modals and dashboards — but add complexity.

We document which segments are static, dynamic, or revalidated with explicit cache tags.

Enterprise adoption

Roll out App Router page-by-page from marketing to authenticated app shell. Keep API routes or route handlers for BFF patterns when mobile apps share backends.