Server-Side Rendering vs. Client-Side Rendering, Key Differences Explained

Rendering plays a crucial role in web development, influencing the performance, user experience, and scalability of applications. Two popular approaches are Server-Side Rendering (SSR) and Client-Side Rendering (CSR). In this post, we’ll explore their differences, pros, cons, and when to use each.

What is Server-Side Rendering (SSR)?

Server-Side Rendering (SSR) involves generating the HTML content of a page on the server before sending it to the browser. This approach ensures that the user gets a fully-rendered page as soon as it loads.

How SSR Works:

1. The browser requests a page from the server.
2. The server processes the request, fetches data, and renders the HTML.
3. The fully-rendered HTML is sent to the browser.
4. The browser displays the content and hydrates JavaScript for interactivity.

Example in Next.js:

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

  return { props: { data } }
}

export default function SSRPage({ data }) {
  return <div>Data: {data.message}</div>
}

What is Client-Side Rendering (CSR)?

Client-Side Rendering (CSR) involves rendering HTML content in the browser using JavaScript. The server only sends the bare minimum HTML, and the rest of the rendering happens on the client side.

How CSR Works:

1. The browser requests a page from the server.
2. The server sends a minimal HTML file with a JavaScript bundle.
3. The browser downloads the JavaScript, fetches data, and renders the content.
4. The user sees the content after rendering is complete.

Example in React.js:

import { useState, useEffect } from 'react'

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

  useEffect(() => {
    fetch('https://api.example.com/data')
      .then((response) => response.json())
      .then((data) => setData(data))
  }, [])

  return <div>{data ? `Data: ${data.message}` : 'Loading...'}</div>
}

Key Differences Between SSR and CSR

Pros and Cons of SSR

Pros:

• Improved SEO: Fully-rendered HTML is sent to the client, making it easier for search engines to index.
• Faster Initial Load: Users see meaningful content quickly.
• Better for Low-Power Devices: Reduces the client-side workload.

Cons:

• Higher Server Load: Server renders the page for every request.
• Increased Latency: If server response is slow, users may experience delays.
• Complex Caching: Harder to implement caching compared to static rendering.

Pros and Cons of CSR

Pros:

• Better Interactivity: Ideal for Single-Page Applications (SPAs).
• Reduced Server Load: Shifts rendering to the client.
• Scalable: No server-side rendering bottlenecks for high-traffic apps.

Cons:

• SEO Challenges: Search engines may struggle to index JavaScript-rendered pages.
• Slower Initial Load: Users see a blank or loading screen before content renders.
• Dependent on JavaScript: Requires users to have JavaScript enabled.

When to Use SSR vs. CSR

Use SSR When:

• SEO is critical (e.g., blogs, e-commerce).
• Content changes dynamically per request.
• Faster time-to-first-byte (TTFB) is essential.

Use CSR When:

• Building SPAs with high interactivity.
• Content is static or changes after user interaction.
• Performance on high-traffic apps is a priority.

Conclusion

Both Server-Side Rendering (SSR) and Client-Side Rendering (CSR) have their advantages and trade-offs. Your choice depends on your application’s requirements, such as performance, interactivity, and SEO.

• SSR: Best for SEO and content-heavy applications.
• CSR: Ideal for SPAs and interactive apps.

Understanding these differences will help you make informed decisions when building your next web application.