Next.js
App Router, the caching model, and what it takes to ship it.
18 topics
The App Router Mental Model
How the file system becomes a route tree, what each special file does, and why layouts persisting across navigation is the idea everything else rests on.
core25 minRendering Strategies
Static, dynamic, streamed and partially prerendered — what each costs, and how Next 16 decides which one a route gets.
core30 minServer vs Client Components
Where the boundary goes, what crosses it, and why 'use client' marks an entry point rather than a single component.
core25 minData Fetching in the App Router
Fetching on the server with await, avoiding waterfalls, and the handful of patterns that cover almost every case.
core25 minThe Next.js Caching Model
What is cached, for how long, and how to invalidate it — including everything that changed in Next 15 and 16.
core35 minStreaming & Loading UI
Where loading.tsx and Suspense boundaries actually belong, and why boundary placement decides how fast a page feels.
core20 minServer Actions
Functions that run on the server but are called like a client callback — how the RPC works, and why every one of them is a public endpoint.
core25 minRoute Handlers
Building HTTP endpoints in app/, when you actually need one, and how they differ from server actions and from Pages Router API routes.
core20 minProxy, Middleware & the Edge Runtime
The request-level hook that runs before routing — renamed to proxy in Next 16 — and why it should stay thin.
core20 minAuthentication in Next.js
Where sessions live, where authorisation is actually enforced, and why the layout you thought was protecting a route is not.
core30 minError & Not-Found Handling
The error, not-found and global-error conventions, what each one catches, and how to fail without losing the whole page.
core20 minMetadata & SEO
The Metadata API, generateMetadata, and the handful of things that actually decide whether a Next app is indexable.
core20 minImages, Fonts & Assets
What next/image and next/font actually do for your Core Web Vitals, and the Next 16 defaults that changed underneath them.
core20 minEnvironment Config & Secrets
Which variables reach the browser, why NEXT_PUBLIC values are baked in at build time, and what replaced runtime config in Next 16.
core20 minInternationalised Routing
Locale in the URL, dictionaries loaded on the server, and the parts of i18n that are not translation.
deep20 minBundle & Payload Budgets
What actually ships to the browser in an App Router app, how to see it, and the levers that move the number.
core25 minDeployment, Runtimes & Hosting
What a Next build actually produces, what self-hosting requires, and where the Vercel-shaped assumptions leak.
core25 minMigrating Pages to App Router
Running both routers side by side, the API-by-API translation table, and how to sequence a migration that never blocks feature work.
deep25 min