ISR (Incremental Static Regeneration)
ISR (Incremental Static Regeneration) is a Next.js rendering strategy: pages are served as static HTML while being regenerated in the background on a set interval — combining static speed with content freshness.
Using ISR in Next.js
// App Router: set the revalidation interval in seconds
export const revalidate = 3600;- SSG:
export const dynamic = 'force-static'— generated at build time, never auto-updates. - ISR: set
revalidate— the first request after expiry triggers background regeneration.
Marketing blogs and programmatic pages typically start with SSG and migrate to ISR as they scale.
FAQ
What is the difference between ISR and SSG?
SSG generates all pages at build time, so content updates require a full rebuild; ISR adds background regeneration on top of SSG — pages refresh on access or on expiry without rebuilding the whole site.
Should a marketing site use SSG or ISR?
Pure SSG is simplest when content is small (hundreds of pages); once programmatic pages reach tens of thousands or content updates hourly, ISR avoids lengthy full builds.