Caching

These rules identify patterns that bypass Vercel's CDN and ISR caching, forcing unnecessary server-side rendering and increasing compute costs.

Version-aware behavior

Caching diagnostics adapt to the detected Next.js major version:

• Next.js 15: warnings emphasize that fetch and GET handlers are uncached by default.
• Next.js 16+: warnings prioritize Cache Components guidance ("use cache", cache tags, targeted revalidation).
• Other/unknown versions: warnings use framework-agnostic cache policy guidance.

nextjs-no-side-effect-in-get-handler

Detects GET route handlers that contain side effects (mutating cookies, headers, or database calls) or are on mutating route segments like /logout, /signout, /delete, etc.

Why it matters: GET requests can be triggered by prefetching and are vulnerable to CSRF. Side effects in GET handlers also prevent caching.

// app/api/logout/route.ts
export async function GET() {
  cookies().delete("session");
  return Response.json({ ok: true });
}

// app/api/logout/route.ts
export async function POST() {
  cookies().delete("session");
  return Response.json({ ok: true });
}

Detected mutating route segments: logout, log-out, signout, sign-out, unsubscribe, delete, remove, revoke, cancel, deactivate.

vercel-no-force-dynamic

Detects pages with export const dynamic = "force-dynamic".

Why it matters: force-dynamic forces server-side rendering on every request, completely bypassing full-page caching.

export const dynamic = "force-dynamic";

export default function Page() { ... }

export const revalidate = 3600;

export default function Page() { ... }

vercel-no-no-store-fetch

Detects fetch calls with cache: "no-store" or revalidate: 0.

Why it matters: These options disable caching entirely, increasing uncached bandwidth and compute costs on every request.

const data = await fetch(url, { cache: "no-store" });

const data = await fetch(url, {
  next: { revalidate: 3600 },
});

vercel-missing-cache-policy

Detects GET route handlers without any explicit cache configuration — no Cache-Control headers, no revalidate export, and no dynamic export.

Why it matters: Without an explicit cache policy, responses may miss CDN caching opportunities, causing repeated origin hits.

export async function GET() {
  const data = await fetchData();
  return Response.json(data);
}

export const revalidate = 3600;

export async function GET() {
  const data = await fetchData();
  return Response.json(data);
}

vercel-prefer-get-static-props

Detects Pages Router routes using getServerSideProps.

Why it matters: getServerSideProps runs on every request. Switching to getStaticProps (with optional ISR) caches pages at the CDN and reduces server compute.

vercel-get-static-props-consider-isr

Detects getStaticProps without a revalidate return value.

Why it matters: Without revalidate, all pages are built at deploy time. For large sites this slows builds dramatically. ISR generates pages on-demand and caches them.

export async function getStaticProps() {
  const data = await fetchData();
  return {
    props: { data },
    revalidate: 3600,
  };
}