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Incremental Static Regeneration (ISR)

Incremental Static Regeneration (ISR) is a technique in web development that allows static pages to be incrementally updated with new content while maintaining the performance benefits of static site generation. This technology is supported by frameworks like Next.js, enabling developers to fetch and render fresh content without requiring a full site rebuild.

What is Incremental Static Regeneration (ISR)?

Incremental Static Regeneration (ISR) is an advanced web development technique that combines the benefits of static site generation (SSG) with the flexibility of server-side rendering (SSR). ISR enables developers to incrementally update static pages with fresh content without having to rebuild the entire site. This ensures that users get the performance advantages of static sites, such as fast load times and improved SEO, while still keeping the content up-to-date.

Static Site Generation typically involves pre-rendering all pages of a website at build time, which can be time-consuming and resource-intensive for large sites. ISR, on the other hand, allows for the regeneration of individual static pages as needed, based on a specified schedule or when new content is available. This is particularly useful for sites that require frequent updates, such as blogs, e-commerce stores, and news websites.

Core Features of ISR

On-Demand Updates

One of the standout features of ISR is its capability to serve updated content on-demand. Unlike traditional static sites that require a full rebuild to update content, ISR can refresh individual pages by re-rendering them at runtime. For instance, if a blog post is updated, only that specific page is re-generated and served to new visitors.

Performance Optimization

ISR maintains the high performance of static sites by serving pre-rendered pages that load quickly. The technique takes advantage of Content Delivery Networks (CDNs) to cache and distribute the static content globally, ensuring users experience faster load times regardless of their location.

SEO Benefits

Search engines favor websites that load quickly and provide up-to-date content. With ISR, the SEO advantages are twofold: the site benefits from the fast load times of static pages, and the content remains current, which can improve search engine rankings.

How Does ISR Work?

ISR works by re-rendering static pages on the server side and caching them for future requests. Here's a simplified explanation of the process:

  1. Build Time: Initially, all static pages are pre-rendered and stored in a CDN.
  2. Cache Invalidation: Developers specify a revalidation period, after which the CDN checks if the content needs to be updated.
  3. Content Updates: If an update is required, the server fetches the new content, re-renders the page, and caches the updated version.
  4. Serving Pages: Users requesting the page during the revalidation phase will see the cached version until the new page is generated.

Benefits of Using ISR


ISR is highly scalable, making it suitable for sites with large amounts of content. As the site grows, developers can update only the necessary pages without affecting the entire site, saving time and computing resources.


By bridging the gap between SSG and SSR, ISR offers flexibility in how and when content is updated. This approach is particularly beneficial for dynamic sites that need frequent updates while maintaining static site performance.

Cost Efficiency

ISR can potentially reduce costs associated with server resources and build times. Since only specific pages are regenerated, the overall load on the server is minimized, leading to lower hosting and maintenance costs.

Comparison with Other Rendering Methods

Static Site Generation (SSG)

SSG pre-renders all pages at build time, which guarantees fast load times but can be resource-intensive for large or frequently updated sites.

Server-Side Rendering (SSR)

SSR renders pages on-the-fly for each request, ensuring the content is always up-to-date but often results in slower performance compared to static sites.

Client-Side Rendering (CSR)

CSR relies on JavaScript to render pages in the browser, which can lead to slower initial load times and potential SEO challenges.

Practical Use Cases for ISR

E-commerce Sites

ISR is ideal for e-commerce platforms that need to display the latest product information, prices, and stock availability. By incrementally updating product pages, the site can ensure customers always see current data without compromising on performance.

News Websites

News sites benefit from ISR by delivering up-to-date articles and stories. Rather than rebuilding the entire site for each new post, ISR allows for quick updates of individual news pages.

Blogs and Content-Rich Sites

For content-heavy sites like blogs, ISR provides a mechanism to update articles or pages frequently without a full site rebuild, ensuring content remains fresh and relevant to readers.

Frameworks Supporting ISR


Next.js is one of the most popular frameworks that natively support ISR. With Next.js, developers can easily implement ISR by defining revalidation times and leveraging the framework's built-in features to manage incremental updates.


Although Gatsby primarily focuses on static site generation, it has also introduced features that support incremental builds, allowing for faster updates and improved build times.

How to Implement ISR with Next.js

Implementing ISR in Next.js involves setting the revalidate property in the getStaticProps function. Here's a basic example:

export async function getStaticProps() {
  const data = await fetchData();

  return {
    props: { data },
    revalidate: 60, // revalidate every 60 seconds

This configuration ensures that the page is regenerated at most once per 60 seconds, fetching the latest content for users.


Incremental Static Regeneration (ISR) is revolutionizing the way developers approach static site generation by offering the best of both worlds—performance and freshness. Whether you're running a blog, an e-commerce site, or a news platform, ISR provides the tools necessary to keep your content current without sacrificing speed.

Ready to transform your web experience with ISR? Use wisp to power your content and see the benefits firsthand! For more insights, check out this detailed overview by Next.js.

Learn more about related concepts like Static Site Generation (SSG) and Server-Side Rendering (SSR) on our Wisp Glossary.