No,Category,Guideline,Description,Do,Don't,Code Good,Code Bad,Severity,Docs URL
1,Routing,Use App Router for new projects,App Router is the recommended approach in Next.js 15+,app/ directory with page.tsx,pages/ for new projects,app/dashboard/page.tsx,pages/dashboard.tsx,Medium,https://nextjs.org/docs/app
2,Routing,Use file-based routing,Create routes by adding files in app directory,page.tsx for routes layout.tsx for layouts,Manual route configuration,app/blog/[slug]/page.tsx,Custom router setup,Medium,https://nextjs.org/docs/app/building-your-application/routing
3,Routing,Colocate related files,Keep components styles tests with their routes,Component files alongside page.tsx,Separate components folder,app/dashboard/_components/,components/dashboard/,Low,
4,Routing,Use route groups for organization,Group routes without affecting URL,Parentheses for route groups,Nested folders affecting URL,(marketing)/about/page.tsx,marketing/about/page.tsx,Low,https://nextjs.org/docs/app/building-your-application/routing/route-groups
5,Routing,Handle loading states,Use loading.tsx for route loading UI,loading.tsx alongside page.tsx,Manual loading state management,app/dashboard/loading.tsx,useState for loading in page,Medium,https://nextjs.org/docs/app/building-your-application/routing/loading-ui-and-streaming
6,Routing,Handle errors with error.tsx,Catch errors at route level,error.tsx with reset function,try/catch in every component,app/dashboard/error.tsx,try/catch in page component,High,https://nextjs.org/docs/app/building-your-application/routing/error-handling
7,Rendering,Use Server Components by default,Server Components reduce client JS bundle,Keep components server by default,Add 'use client' unnecessarily,export default function Page(),('use client') for static content,High,https://nextjs.org/docs/app/building-your-application/rendering/server-components
8,Rendering,Mark Client Components explicitly,'use client' for interactive components,Add 'use client' only when needed,Server Component with hooks/events,('use client') for onClick useState,No directive with useState,High,https://nextjs.org/docs/app/building-your-application/rendering/client-components
9,Rendering,Push Client Components down,Keep Client Components as leaf nodes,Client wrapper for interactive parts only,Mark page as Client Component,<InteractiveButton/> in Server Page,('use client') on page.tsx,High,
10,Rendering,Use streaming for better UX,Stream content with Suspense boundaries,Suspense for slow data fetches,Wait for all data before render,<Suspense><SlowComponent/></Suspense>,await allData then render,Medium,https://nextjs.org/docs/app/building-your-application/routing/loading-ui-and-streaming
11,Rendering,Choose correct rendering strategy,SSG for static SSR for dynamic ISR for semi-static,generateStaticParams for known paths,SSR for static content,export const revalidate = 3600,fetch without cache config,Medium,
12,DataFetching,Fetch data in Server Components,Fetch directly in async Server Components,async function Page() { const data = await fetch() },useEffect for initial data,const data = await fetch(url),useEffect(() => fetch(url)),High,https://nextjs.org/docs/app/building-your-application/data-fetching
13,DataFetching,Configure caching explicitly (Next.js 15+),Next.js 15 changed defaults to uncached for fetch,Explicitly set cache: 'force-cache' for static data,Assume default is cached (it's not in Next.js 15),fetch(url { cache: 'force-cache' }),fetch(url) // Uncached in v15,High,https://nextjs.org/docs/app/building-your-application/upgrading/version-15
14,DataFetching,Deduplicate fetch requests,React and Next.js dedupe same requests,Same fetch call in multiple components,Manual request deduplication,Multiple components fetch same URL,Custom cache layer,Low,
15,DataFetching,Use Server Actions for mutations,Server Actions for form submissions,action={serverAction} in forms,API route for every mutation,<form action={createPost}>,<form onSubmit={callApiRoute}>,Medium,https://nextjs.org/docs/app/building-your-application/data-fetching/server-actions-and-mutations
16,DataFetching,Revalidate data appropriately,Use revalidatePath/revalidateTag after mutations,Revalidate after Server Action,'use client' with manual refetch,revalidatePath('/posts'),router.refresh() everywhere,Medium,https://nextjs.org/docs/app/building-your-application/caching#revalidating
17,Images,Use next/image for optimization,Automatic image optimization and lazy loading,<Image> component for all images,<img> tags directly,<Image src={} alt={} width={} height={}>,<img src={}/>,High,https://nextjs.org/docs/app/building-your-application/optimizing/images
18,Images,Provide width and height,Prevent layout shift with dimensions,width and height props or fill,Missing dimensions,<Image width={400} height={300}/>,<Image src={url}/>,High,
19,Images,Use fill for responsive images,Fill container with object-fit,fill prop with relative parent,Fixed dimensions for responsive,"<Image fill className=""object-cover""/>",<Image width={window.width}/>,Medium,
20,Images,Configure remote image domains,Whitelist external image sources,remotePatterns in next.config.js,Allow all domains,remotePatterns: [{ hostname: 'cdn.example.com' }],domains: ['*'],High,https://nextjs.org/docs/app/api-reference/components/image#remotepatterns
21,Images,Use priority for LCP images,Mark above-fold images as priority,priority prop on hero images,All images with priority,<Image priority src={hero}/>,<Image priority/> on every image,Medium,
22,Fonts,Use next/font for fonts,Self-hosted fonts with zero layout shift,next/font/google or next/font/local,External font links,import { Inter } from 'next/font/google',"<link href=""fonts.googleapis.com""/>",Medium,https://nextjs.org/docs/app/building-your-application/optimizing/fonts
23,Fonts,Apply font to layout,Set font in root layout for consistency,className on body in layout.tsx,Font in individual pages,<body className={inter.className}>,Each page imports font,Low,
24,Fonts,Use variable fonts,Variable fonts reduce bundle size,Single variable font file,Multiple font weights as files,Inter({ subsets: ['latin'] }),Inter_400 Inter_500 Inter_700,Low,
25,Metadata,Use generateMetadata for dynamic,Generate metadata based on params,export async function generateMetadata(),Hardcoded metadata everywhere,generateMetadata({ params }),export const metadata = {},Medium,https://nextjs.org/docs/app/building-your-application/optimizing/metadata
26,Metadata,Include OpenGraph images,Add OG images for social sharing,opengraph-image.tsx or og property,Missing social preview images,opengraph: { images: ['/og.png'] },No OG configuration,Medium,
27,Metadata,Use metadata API,Export metadata object for static metadata,export const metadata = {},Manual head tags,export const metadata = { title: 'Page' },<head><title>Page</title></head>,Medium,
28,API,Use Route Handlers for APIs,app/api routes for API endpoints,app/api/users/route.ts,pages/api for new projects,export async function GET(request),export default function handler,Medium,https://nextjs.org/docs/app/building-your-application/routing/route-handlers
29,API,Return proper Response objects,Use NextResponse for API responses,NextResponse.json() for JSON,Plain objects or res.json(),return NextResponse.json({ data }),return { data },Medium,
30,API,Handle HTTP methods explicitly,Export named functions for methods,Export GET POST PUT DELETE,Single handler for all methods,export async function POST(),switch(req.method),Low,
31,API,Validate request body,Validate input before processing,Zod or similar for validation,Trust client input,const body = schema.parse(await req.json()),const body = await req.json(),High,
32,Middleware,Use middleware for auth,Protect routes with middleware.ts,middleware.ts at root,Auth check in every page,export function middleware(request),if (!session) redirect in page,Medium,https://nextjs.org/docs/app/building-your-application/routing/middleware
33,Middleware,Match specific paths,Configure middleware matcher,config.matcher for specific routes,Run middleware on all routes,matcher: ['/dashboard/:path*'],No matcher config,Medium,
34,Middleware,Keep middleware edge-compatible,Middleware runs on Edge runtime,Edge-compatible code only,Node.js APIs in middleware,Edge-compatible auth check,fs.readFile in middleware,High,
35,Environment,Use NEXT_PUBLIC prefix,Client-accessible env vars need prefix,NEXT_PUBLIC_ for client vars,Server vars exposed to client,NEXT_PUBLIC_API_URL,API_SECRET in client code,High,https://nextjs.org/docs/app/building-your-application/configuring/environment-variables
36,Environment,Validate env vars,Check required env vars exist,Validate on startup,Undefined env at runtime,if (!process.env.DATABASE_URL) throw,process.env.DATABASE_URL (might be undefined),High,
37,Environment,Use .env.local for secrets,Local env file for development secrets,.env.local gitignored,Secrets in .env committed,.env.local with secrets,.env with DATABASE_PASSWORD,High,
38,Performance,Analyze bundle size,Use @next/bundle-analyzer,Bundle analyzer in dev,Ship large bundles blindly,ANALYZE=true npm run build,No bundle analysis,Medium,https://nextjs.org/docs/app/building-your-application/optimizing/bundle-analyzer
39,Performance,Use dynamic imports,Code split with next/dynamic,dynamic() for heavy components,Import everything statically,const Chart = dynamic(() => import('./Chart')),import Chart from './Chart',Medium,https://nextjs.org/docs/app/building-your-application/optimizing/lazy-loading
40,Performance,Avoid layout shifts,Reserve space for dynamic content,Skeleton loaders aspect ratios,Content popping in,"<Skeleton className=""h-48""/>",No placeholder for async content,High,
41,Performance,Use Partial Prerendering,Combine static and dynamic in one route,Static shell with Suspense holes,Full dynamic or static pages,Static header + dynamic content,Entire page SSR,Low,https://nextjs.org/docs/app/building-your-application/rendering/partial-prerendering
42,Link,Use next/link for navigation,Client-side navigation with prefetching,"<Link href=""""> for internal links",<a> for internal navigation,"<Link href=""/about"">About</Link>","<a href=""/about"">About</a>",High,https://nextjs.org/docs/app/api-reference/components/link
43,Link,Prefetch strategically,Control prefetching behavior,prefetch={false} for low-priority,Prefetch all links,<Link prefetch={false}>,Default prefetch on every link,Low,
44,Link,Use scroll option appropriately,Control scroll behavior on navigation,scroll={false} for tabs pagination,Always scroll to top,<Link scroll={false}>,Manual scroll management,Low,
45,Config,Use next.config.js correctly,Configure Next.js behavior,Proper config options,Deprecated or wrong options,images: { remotePatterns: [] },images: { domains: [] },Medium,https://nextjs.org/docs/app/api-reference/next-config-js
46,Config,Enable strict mode,Catch potential issues early,reactStrictMode: true,Strict mode disabled,reactStrictMode: true,reactStrictMode: false,Medium,
47,Config,Configure redirects and rewrites,Use config for URL management,redirects() rewrites() in config,Manual redirect handling,redirects: async () => [...],res.redirect in pages,Medium,https://nextjs.org/docs/app/api-reference/next-config-js/redirects
48,Deployment,Use Vercel for easiest deploy,Vercel optimized for Next.js,Deploy to Vercel,Self-host without knowledge,vercel deploy,Complex Docker setup for simple app,Low,https://nextjs.org/docs/app/building-your-application/deploying
49,Deployment,Configure output for self-hosting,Set output option for deployment target,output: 'standalone' for Docker,Default output for containers,output: 'standalone',No output config for Docker,Medium,https://nextjs.org/docs/app/building-your-application/deploying#self-hosting
50,Security,Sanitize user input,Never trust user input,Escape sanitize validate all input,Direct interpolation of user data,DOMPurify.sanitize(userInput),dangerouslySetInnerHTML={{ __html: userInput }},High,
51,Security,Use CSP headers,Content Security Policy for XSS protection,Configure CSP in next.config.js,No security headers,headers() with CSP,No CSP configuration,High,https://nextjs.org/docs/app/building-your-application/configuring/content-security-policy
52,Security,Validate Server Action input,Server Actions are public endpoints,Validate and authorize in Server Action,Trust Server Action input,Auth check + validation in action,Direct database call without check,High,
53,Next15,Async Request APIs,Next.js 15 makes cookies headers params async,await cookies() await headers() await params,Synchronous access to request APIs,const cookieStore = await cookies(),const cookieStore = cookies(),High,https://nextjs.org/docs/app/building-your-application/upgrading/version-15
54,Next15,Caching default changes,fetch requests are no longer cached by default,Explicitly opt into caching with cache: 'force-cache',Assume requests are cached,"fetch(url, { cache: 'force-cache' })",fetch(url) expecting cache,High,https://nextjs.org/docs/app/building-your-application/upgrading/version-15#fetch-requests
55,Next15,Turbopack for development,Turbopack is stable for dev in Next.js 15,Use --turbo flag for faster dev builds,Webpack for all development,next dev --turbo,next dev,Medium,https://nextjs.org/docs/app/api-reference/turbopack
56,Next15,Partial Prerendering (experimental),Combine static shell with dynamic content,Enable PPR for mixed static/dynamic pages,Full SSR or full static,"experimental: { ppr: 'incremental' }",No PPR configuration,Low,https://nextjs.org/docs/app/building-your-application/rendering/partial-prerendering
57,Next15,unstable_after API,Execute code after response is sent,after() for analytics logging cleanup,Block response for side effects,after(() => { logAnalytics() }),await logAnalytics() before response,Low,https://nextjs.org/docs/app/api-reference/functions/unstable_after
58,Next15,Instrumentation hook,Run code at server startup,instrumentation.ts for monitoring setup,Initialize in middleware or routes,export async function register() {},Initialize in first route hit,Medium,https://nextjs.org/docs/app/building-your-application/optimizing/instrumentation
59,Next15,Enhanced Forms,next/form component for client-side navigation,<Form> with automatic prefetching,Standard form without navigation benefit,import { Form } from 'next/form',<form action={...}>,Low,https://nextjs.org/docs/app/api-reference/components/form
60,Next15,TypeScript config support,next.config.ts with full TypeScript,Use next.config.ts for type safety,JavaScript config only,next.config.ts with types,next.config.js,Low,https://nextjs.org/docs/app/building-your-application/configuring/typescript
61,View Transitions,Use View Transitions with next/link,Next.js supports View Transitions API natively for smooth page transitions,Add viewTransition prop to Link component,Manual DOM manipulation for page transitions,"<Link viewTransition href=""/about"">About</Link>",router.push() without transition handling,Medium,https://nextjs.org/docs/app/api-reference/components/link#viewtransition
62,View Transitions,Configure View Transitions globally,Enable experimental view transitions in next.config.js for app-wide support,Enable in experimental config section,Forget browser support varies across browsers,"experimental: { viewTransition: true }",No viewTransition configuration,Medium,https://nextjs.org/docs/app/api-reference/config/next-config-js/viewTransition
63,View Transitions,View Transition with useTransitionRouter,Use transition-aware navigation with React startTransition for smooth UI updates,Use startTransition with router navigation,Direct push without transition context,"startTransition(() => router.push('/page'))",router.push('/page') without transition,Low,https://nextjs.org/docs/app/building-your-application/routing/linking-and-navigating
64,Next16,Next.js 16 requires React 19+,Next.js 16 fully embraces React 19 features including Server Components Actions and Compiler,Ensure React 19.2+ is installed with Next.js 16,Use React 18 with Next.js 16,"""react"": ""^19.2.0"" ""next"": ""^16.0.0""","""react"": ""^18.2.0"" ""next"": ""^16.0.0""",High,https://nextjs.org/docs/app/building-your-application/upgrading/version-16
65,Next16,Use Turbopack for both dev and build,Turbopack is now fully stable in Next.js 16 for development and production builds,next build --turbopack for faster builds,Stick with Webpack for production,next build --turbopack,next build (webpack slower),Medium,https://nextjs.org/docs/app/api-reference/turbopack
66,Next16,Use new caching directives,Next.js 16 introduces more granular caching control with use cache directive,Use cache directives for dynamic data,Rely only on fetch cache options,'use cache'; export default async function Page() {},Manual revalidate logic everywhere,Medium,https://nextjs.org/docs/app/building-your-application/caching
67,Next16,Enable React Compiler in Next.js 16,Next.js 16 has built-in support for React Compiler for automatic optimization,Enable experimental.reactCompiler in next.config,Manual useMemo/useCallback when Compiler handles it,"experimental: { reactCompiler: true }",Extensive manual memoization,High,https://nextjs.org/docs/app/api-reference/config/next-config-js/reactCompiler
68,Next16,Leverage improved streaming,Next.js 16 improves streaming performance with better Suspense boundary handling,Use loading.tsx and Suspense for streaming,Block entire page on slow data,export default function Loading() { return <Skeleton />; },await slowData before render,Medium,https://nextjs.org/docs/app/building-your-application/routing/loading-ui-and-streaming
