What's the difference between SSR and SSG?

With SSG the page is generated at build time – everyone gets the same HTML, very fast and cheap to host. With SSR the page is generated on the server on each request – good for personalized or frequently changing content.

Which is better for SEO?

Both are great for SEO – content is in the HTML that search engines receive. SSG is even faster, which also helps Core Web Vitals. What matters is that content is available on first load, without waiting for JavaScript.

Incremental Static Regeneration – the page is static but can be regenerated in the background after a set interval (e.g. every 60 seconds). It combines SSG speed with the ability to update without a full rebuild.

When should I use dynamic rendering (SSR)?

When content depends on the user (profile, cart), on frequently changing data (prices, availability), or on the request (geolocation, cookies). For static marketing or blog, SSG is a better fit.

Does Next.js App Router change this?

In App Router, components are Server Components by default. For static content the page is generated at build. For dynamic you use fetch with cache options or dynamic functions. generateStaticParams replaces getStaticPaths.

Next.js – SSR, Static Generation and When to Use What

Next.js – SSR, Static Generation and Strategy

Next.js gives you several ways to serve content: statically at build time, on the server per request, or a mix with periodic revalidation. Understanding these options is key for speed, SEO, and infrastructure cost.

Static Generation (SSG)

With Static Site Generation each page is built once during next build. The result is HTML files served directly from CDN or web server. No computation on request – just file delivery.

Benefits: maximum speed, low server load, cheap hosting (even static-only), great for SEO and Core Web Vitals.

Best for: marketing pages, blog, docs, catalogs with rarely changing content. In App Router, pages are static by default unless you use dynamic functions or dynamic fetch.

Server-Side Rendering (SSR)

With Server-Side Rendering the page is generated on every request. The server runs your code, fetches data (DB, API), renders React to HTML and sends the response. Each user can get different content.

Benefits: always fresh data, room for personalization, content based on cookies or headers.

Drawbacks: higher server load, slower than a static file (still usually under a second with good infrastructure).

Best for: dashboards, personalized portals, real-time data pages, content behind auth.

Incremental Static Regeneration (ISR)

ISR is a hybrid: the page is generated statically, but after a set period (e.g. 60 seconds) the next request triggers regeneration in the background. Users always get a fast response; content updates without a full rebuild.

Good for: news sites, product catalogs with prices – when you want SSG speed and periodic updates.

App Router – How You Control It

In Next.js 13+ App Router components are Server Components by default and pages can be static. To make a page dynamic (SSR), you use dynamic functions like cookies(), headers(), or searchParams in the page, or set export const dynamic = 'force-dynamic'.

For static pages with dynamic segments (e.g. /blog/[slug]) you use generateStaticParams() – Next.js will pregenerate all combinations at build. To mix pregenerated and on-demand pages you combine generateStaticParams with dynamicParams.

Practical Choice

| Scenario | Recommendation | |----------|----------------| | Marketing, blog, landing | SSG (default in App Router) | | Frequently changing content | ISR with suitable revalidate | | Personalization, user data | SSR | | Mixed site | SSG for most pages, SSR for specific routes |

Choosing the right strategy avoids unnecessary server load and keeps loading fast and SEO-friendly where possible.

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