SSR vs SSG in Next.js: Static vs Server Rendering Explained

Introduction

Next.js, a widely used React framework, has revolutionized modern web development by providing various rendering strategies that enhance application performance and user experience. It offers multiple rendering techniques, including Server-Side Rendering (SSR) and Static Site Generation (SSG). Each method plays a crucial role in optimizing page load times, SEO, and content delivery.

Server-Side Rendering (SSR) dynamically generates page content on the server for each request, delivering fresh HTML to the client’s browser. This approach shines for apps requiring real-time data, like user dashboards or personalized feeds. In contrast, Static Site Generation (SSG) pre-renders pages at build time, producing lightning-fast static HTML files perfect for content-heavy sites like blogs, portfolios, or e-commerce product pages.

In this article, we’ll learn SSG vs SSR in Next.js, breaking down their core differences and advantages.

Server-Side Rendering (SSR)

Server-Side Rendering (SSR) is a technique where a web page is fully rendered on the server before being sent to the client’s browser. When a user requests a page, the server processes the data, generates the HTML content, and sends it as a ready-to-display page. This ensures search engines can crawl and index the content immediately, making SSR a powerful tool for SEO and improving initial load performance.

How SSR Works in Next.js

• Client Request: A user visits a page (e.g., a product listing).
• Server Processing: The server fetches real-time data (e.g., product availability) and generates the complete HTML.
• HTML Delivery: The server sends the fully rendered HTML to the browser.
• Hydration: React takes over on the client side, making the page interactive.

Pros of SSR in Next.js

• Dynamic Content: SSR generates real-time, personalized pages on the server, making it ideal for News platforms, Live dashboards, E-commerce sites (displaying user-specific recommendations).
• SEO-Friendly: SSR delivers fully rendered HTML to search engines, improving crawlability and indexing.
• Flexibility: Easily integrate with databases (e.g., PostgreSQL), APIs, or CMS platforms.

Cons of SSR in Next.js

• Performance Overhead: Generating pages on every request increases Time to First Byte (TTFB), especially for pages with heavy computations or nested API calls.
• Scalability Challenges: High traffic can strain server resources, requiring robust infrastructure (e.g., AWS, Vercel Serverless Functions).
• Higher Costs: Frequent server-side rendering demands more compute power, raising hosting expenses.

Best Use Cases for Server-Side Rendering (SSR) in Next.js

The best time to use Server-Side Rendering (SSR) in Next.js is for applications that rely on frequently updated data, real-time information, or user-specific content. For example, e-commerce platforms benefit from SSR when displaying dynamic product details like pricing, availability, or personalized recommendations. Similarly, dashboards that showcase live analytics, financial data, or user-specific metrics are perfect candidates for SSR, as they require real-time updates and tailored experiences. Social media platforms also leverage SSR to deliver personalized feeds and notifications, ensuring users see the most relevant content instantly.

SSR is not just recommended but essential in scenarios where dynamic content and customized interactions are critical. Its ability to generate fully rendered HTML on the server ensures SEO-friendly pages and seamless user experiences, making it indispensable for apps that demand both performance and personalization.

How to Implement SSR in Next.js (App Router)

With the Next.js App Router (introduced in Next.js 13+), we can implement Server-Side Rendering (SSR) using React Server Components (RSC) and the fetch API inside a server component.

Create an SSR Page in App Router

Next.js automatically enables SSR in server components. You just need to define an async function inside the app/ directory.

1  // app/ssr-example/page.tsx (App Router SSR Example)
2export default async function SSRPage() {
3// Fetch data on the server
4const res = await fetch('https://api.example.com/data', { cache: 'no-store' }); 
5const data = await res.json();
6
7return (
8  <div>
9    <h1>Server-Side Rendering Example</h1>
10    <p>Data fetched from API: {data.title}</p>
11  </div>
12);
13} 

Key Points:

• Server Components are default in App Router, so no need for getServerSideProps.
• fetch runs on the server and prevents unnecessary client-side execution.
• cache: 'no-store' ensures fresh data is fetched on each request.

Static Site Generation (SSG)

Static Site Generation (SSG) is a Next.js technique that pre-renders pages at build time, serving them as static HTML files. This approach delivers instant load speeds and is ideal for content that rarely changes, while still maintaining SEO benefits through pre-rendered pages.

How SSG Works in Next.js

• Build Phase: Pages are pre-rendered during deployment.
• HTML Serving: Static files are cached and served instantly to users.
• HTML Delivery: The server sends the fully rendered HTML to the browser.
• Client Hydration: React adds interactivity after initial load.

Pros of SSG in Next.js

• Lightning Speed: Instant page loads with pre-built HTML.
• SEO Optimized: Fully rendered HTML for search engines.
• Cost-Effective: Minimal server processing required.
• Scalability: Easily handles high traffic with CDN caching.

Cons of SSG in Next.js

• Static Content: Not ideal for real-time/personalized data.
• Rebuild Required: Content updates need redeployment.
• Build Time: Large sites may require longer build processes.

Best Use Cases for SSG in Next.js

SSG excels for content-focused sites like blogs, marketing pages, and documentation. Examples:

• Blogs/Portfolios: Pre-render articles at build time.
• E-commerce Catalogs: Static product listings with ISR updates.
• Documentation Sites: Versioned content requiring SEO.

How to Implement SSG in Next.js (App Router)

Next.js App Router enables SSG using cache: 'force-cache' or revalidate with fetch.

Create an SSR Page in App Router

Next.js automatically enables SSR in server components. You just need to define an async function inside the app/ directory.

1// app/products/[id]/page.tsx  
2export default async function ProductPage({ params }: { params: { id: string } }) {  
3// SSG with Incremental Static Regeneration (ISR)  
4const res = await fetch(`https://api.example.com/products/${params.id}?`, {  
5  next: { revalidate: 3600 } // Revalidate every hour  
6});  
7const product = await res.json();  
8
9return (  
10  <div>  
11    <h1>{product.name}</h1>  
12    <p>Price: ${product.price}</p>  
13  </div>  
14);  
15}  
16
17// Generate static paths at build time  
18export async function generateStaticParams() {  
19const res = await fetch('https://api.example.com/products');  
20const products = await res.json();  
21
22return products.map((p: { id: string }) => ({ id: p.id }));  
23}  

Key Points:

• generateStaticParams: Pre-generates static paths during build.
• revalidate: Enables ISR for periodic updates without redeploying.
• Zero Client-Side Processing: Data fetching happens only at build/revalidation.

Check also Next.js Google Analytics setup and how to Add Google AdSense to Next.js.

Frequently Asked Questions

• Q: When should I use SSG over SSR?

  A: Use SSG for static content like blogs, portfolios, or marketing sites. Choose SSR for real-time data, user-specific content, or frequently updated pages.

• Q: Can I use both SSG and SSR in the same Next.js app?

  A: Yes! Next.js supports hybrid rendering. Use SSG for static pages and SSR for dynamic routes, or leverage Incremental Static Regeneration (ISR) for periodic updates.

• Q: Is SSR better for SEO than SSG?

  A: Both SSR and SSG are SEO-friendly since they deliver fully rendered HTML. The choice depends on whether your content is static (SSG) or dynamic (SSR).

Conclusion

Choosing between Server-Side Rendering (SSR) and Static Site Generation (SSG) in Next.js depends on the specific needs of your project. SSR is perfect for real-time, dynamic content that requires up-to-date data on every request, making it an ideal choice for applications like dashboards, e-commerce sites, and social networks. On the other hand, SSG excels when you're dealing with static, content-heavy pages that don't require frequent updates, such as blogs, documentation, and marketing websites.

In the end, whether you choose SSR or SSG, Next.js provides the flexibility to meet the demands of modern web development, ensuring that your app is both fast and SEO-friendly.

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