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Understanding Server-Side Rendering (SSR) vs. Client-Side Rendering (CSR) in Next.js

4/5/2025, 6:37:55 PM

Mohit Kushwah

In the world of modern web development, performance and user experience are everything. With the rise of frameworks like Next.js, developers are equipped with powerful rendering options like Server-Side Rendering (SSR) and Client-Side Rendering (CSR). But how do you know which one to use? In this blog, we’ll break down SSR and CSR in the context of Next.js, highlighting their differences, use-cases, pros, and cons.

What is Rendering?

Rendering is the process of converting your application code (React components, in the case of Next.js) into HTML that can be shown in the browser. This can be done on the server or client depending on your chosen approach.

What is Server-Side Rendering (SSR)?

Server-Side Rendering means the HTML for a page is generated on the server at the time of the request.

In Next.js:

You use SSR by exporting the getServerSideProps function in your page component:

export async function getServerSideProps(context) {
  const res = await fetch('https://api.example.com/data')
  const data = await res.json()

  return {
    props: { data }, // will be passed to the page component as props
  }
}

Advantages of SSR:

  • SEO-friendly: Search engines can crawl the fully rendered HTML.
  • Fresh Data: Always serves the latest data at the time of the request.
  • Faster First Load (in many cases): The user gets a fully-rendered HTML page quickly.

Disadvantages of SSR:

  • Slower Time to First Byte (TTFB): Because the server has to generate the page on each request.
  • Higher Server Load: Every request triggers data fetching and page rendering.

What is Client-Side Rendering (CSR)?

Client-Side Rendering means the page is rendered in the browser using JavaScript. The initial HTML is minimal and data is fetched after the page loads.

In Next.js:

CSR is the default behavior in traditional React components or when you use hooks like useEffect() to fetch data:

import { useEffect, useState } from 'react'

export default function Page() {
  const [data, setData] = useState(null)

  useEffect(() => {
    fetch('/api/data')
      .then((res) => res.json())
      .then((data) => setData(data))
  }, [])

  return <div>{data ? <p>{data.message}</p> : <p>Loading...</p>}</div>
}

Advantages of CSR:

  • Faster Navigation: Once the app is loaded, transitions between pages are instant.
  • Reduced Server Load: Server serves static files, and the browser handles the logic.
  • Great for Authenticated Pages: Where SEO isn’t a priority.

Disadvantages of CSR:

  • Slower First Load: Users see a blank screen or loader while JavaScript loads and data is fetched.
  • Not Ideal for SEO: Search engines may struggle to index content if it's not pre-rendered.

SSR vs CSR: Key Differences Explained

Rendering Location

  • SSR (Server-Side Rendering): The content is generated on the server for every request, and the fully-rendered HTML is sent to the browser.
  • CSR (Client-Side Rendering): The initial load sends minimal HTML, and the content is rendered on the client-side using JavaScript after the page loads.

SEO Optimization

  • SSR: Great for SEO. Since the HTML is pre-rendered on the server, search engines can easily index the content.
  • CSR: Less SEO-friendly by default. Content is generated after the page load, which might not be visible to search engines unless you implement SEO workarounds.

First Load Speed

  • SSR: The user sees fully-rendered content quickly, though Time To First Byte (TTFB) can be a bit longer because the server has to process the page on the fly.
  • CSR: The initial screen may be blank while JavaScript loads, but once it does, the app becomes very interactive and fast

Data Freshness

  • SSR: Always delivers the most up-to-date data, since the server fetches it with each new request.
  • CSR: Can also fetch fresh data, but this depends on your data fetching strategy (e.g., using hooks like useEffect or SWR)

Best Use-Cases

  • SSR: Ideal for content-heavy and SEO-sensitive pages like blogs, news articles, marketing or landing pages.
  • CSR: Works best for highly interactive sections like dashboards, user-specific content, single-page applications (SPAs), or areas behind authentication.

Hybrid Approach: The Best of Both Worlds

Next.js allows you to combine SSR and CSR within your app. For example, you might use SSR for your homepage and CSR for the dashboard. This flexibility is one of the biggest strengths of Next.js. You can also use Static Site Generation (SSG) and Incremental Static Regeneration (ISR) for even more optimization — but that’s a topic for another blog!

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