When building modern web apps, developers often face the question: Server Side Rendering (SSR) vs Static Site Generation (SSG). Both are powerful rendering methods in Next.js, but they serve different purposes. Choosing the right one can boost your site’s speed, SEO, and user experience.
In this blog, we’ll break down SSR vs SSG, compare their advantages, and explore when to use each.
What is Server Side Rendering (SSR)?
Server Side Rendering (SSR), also written as server-side rendering, means that your web page is generated on the server for each request. In Next.js SSR, this is done with the getServerSideProps function.
How it works:
- A user visits your page.
- The server fetches data and builds the HTML.
- The user receives a fully rendered page.
Example:
Imagine a stock price dashboard or a news feed. The data changes frequently, so SSR ensures that users always see the latest content.
Best for:
- Real-time dashboards
- Personalized content (e.g., user profiles)
- Data that changes on every request
What is Static Site Generation (SSG)?
Static Site Generation (SSG) is when Next.js builds your HTML at build time instead of on every request. In Next.js SSG, this happens using getStaticProps and optionally getStaticPaths.
How it works:
- Pages are pre-rendered during the build.
- The HTML files are cached and served instantly from a CDN.
Example:
Think of a blog or documentation site. The content doesn’t change often, so pre-rendering makes the site blazing fast.
Best for:
- Blogs & articles
- Marketing or landing pages
- Product catalogs with rarely updated data
Next.js SSR vs SSG: Key Differences
| Feature | SSG (Static Site Generation) | SSR (Server Side Rendering) |
| Rendering Time | Build time | Request time |
| Performance | Super fast (cached static files) | Slower (new render per request) |
| SEO | Excellent (pre-rendered HTML) | Excellent (dynamic HTML) |
| Data Freshness | May become outdated | Always up-to-date |
| Scalability | Highly scalable with CDN | Limited by server capacity |
| Use Cases | Blogs, docs, marketing pages | Real-time apps, dashboards |
Real-Life Analogy
Static Site Generation (SSG):
Think of printing a book. Once it’s printed, everyone reads the same copy — super fast, but updates require a reprint.
Server Side Rendering (SSR):
Think of a newspaper delivered daily. It’s always fresh, but it takes more time and effort to produce each edition.
Pros of SSG
- Lightning-fast performance
- Low hosting cost (CDN-friendly)
- Great for SEO
- Highly scalable
Cons of SSG
- Not ideal for rapidly changing content
- Rebuilding is required for updates (unless using ISR)
Pros of SSR
- Always fresh and dynamic data
- Supports personalized content per user
- Excellent SEO
Cons of SSR
- Slower than SSG (server waits for data)
- Higher hosting/server costs
- Scalability challenges under heavy traffic
SSG vs SSR in Next.js – Which One Should You Use?
Use SSG (Static Site Generation in Next.js) if:
- Your content rarely changes (blogs, product pages, landing pages).
- You want maximum speed and scalability.
Use SSR (Server Side Rendering in Next.js) if:
- You need real-time or frequently updated data.
- You’re building personalized dashboards, stock tickers, or e-commerce sites.
Use ISR (Incremental Static Regeneration) if:
- You want the best of both worlds — pre-rendered speed with occasional updates.
