What is SSR in Next.js: Server-Side Rendering Explained

SSR in Next.js means rendering web pages on the server before sending them to the browser. This helps pages load faster and improves SEO by delivering fully built HTML to users.

How It Works

Server-Side Rendering (SSR) in Next.js works by generating the HTML of a page on the server each time a user requests it. Imagine a restaurant kitchen where meals are cooked fresh when ordered, rather than serving pre-made food. Similarly, SSR builds the page fresh on the server for every request.

This means the browser receives a complete HTML page ready to display, instead of waiting for JavaScript to build the page on the client side. This approach improves the speed of the first visible content and helps search engines understand the page better.

Example

This example shows a Next.js page using SSR with the getServerSideProps function to fetch data on the server before rendering.

javascript

import React from 'react';

export async function getServerSideProps() {
  // Simulate fetching data from an API
  const data = { message: 'Hello from SSR!' };

  return {
    props: { data },
  };
}

export default function HomePage({ data }) {
  return (
    <main>
      <h1>{data.message}</h1>
      <p>This page was rendered on the server.</p>
    </main>
  );
}

Output

<h1>Hello from SSR!</h1>
<p>This page was rendered on the server.</p>

When to Use

Use SSR when you want faster initial page loads and better SEO, especially for pages that change often or depend on user data. For example, news sites, blogs, or e-commerce product pages benefit from SSR because search engines can read the full content immediately.

However, SSR can add some server load and slower response times if overused. For static content that rarely changes, Next.js static generation might be better.

Key Points

• SSR renders pages on the server for each request.
• It improves page load speed and SEO.
• Use getServerSideProps in Next.js to enable SSR.
• Best for dynamic content that changes often.
• Not ideal for all pages due to server load.

Key Takeaways

SSR in Next.js renders pages on the server before sending to the browser.

Use SSR to improve initial load speed and SEO for dynamic pages.

Implement SSR with the getServerSideProps function in Next.js.

SSR is best for pages that need fresh data on every request.

Consider server load and use static generation for mostly static pages.