Understanding SSG, SSR, ISR, and CSR: Choosing the Right Rendering Strategy for Your Web App

Introduction

When developing modern web applications, choosing the right rendering method is crucial for performance, SEO, and user experience. In this post, we'll explore four main rendering strategies: SSG (Static Site Generation), SSR (Server-Side Rendering), ISR (Incremental Static Regeneration), and CSR (Client-Side Rendering). Each has its strengths and weaknesses, and knowing when to use them can make a huge difference in your project.

1. Static Site Generation (SSG)

What is it?

SSG pre-generates HTML files at build time and serves them as static assets. This method is excellent for performance and SEO since there is no need for server processing during runtime.

Pros:

• Fast loading times (pre-built static files)
• SEO-friendly
• Can be cached via CDN for scalability

Cons:

• Not suitable for frequently changing data
• Requires a full rebuild for updates (unless using ISR)

Best Use Cases:

• Blogs and documentation sites
• Marketing and landing pages
• Portfolio websites

2. Server-Side Rendering (SSR)

What is it?

SSR generates the HTML on each request at the server level before sending it to the browser. This ensures the user gets fully rendered content upon initial load.

Pros:

• Dynamic content rendering per request
• SEO-friendly (good for content that changes per request)

Cons:

• Slower initial load time compared to SSG
• Higher server costs and processing time

Best Use Cases:

• Personalized dashboards
• Real-time data pages (e.g., stock prices, social feeds)
• E-commerce product pages (where stock/pricing updates frequently)

3. Incremental Static Regeneration (ISR)

What is it?

ISR is an improved version of SSG, allowing static pages to be updated without rebuilding the entire site. It re-generates static pages in the background after a specified time interval.

Pros:

• Best of both worlds: static performance with dynamic updates
• Reduces the need for full site rebuilds
• CDN-friendly for scalability

Cons:

• Requires a framework like Next.js (not natively available in all setups)
• Might show outdated content if regeneration hasn't happened yet

Best Use Cases:

• News websites
• E-commerce with frequently updated inventory
• Blogs with user-generated content

4. Client-Side Rendering (CSR)

What is it?

CSR shifts the rendering process to the browser using JavaScript (e.g., React, Vue). The initial HTML is minimal, and the app fetches and renders data on the client side.

Pros:

• Fast navigation after the initial load (SPA experience)
• Reduces server load
• Good for highly interactive applications

Cons:

• Slower initial load (JS needs to execute before rendering)
• SEO challenges (unless using hydration techniques like SSR)

Best Use Cases:

• Web apps with heavy interactivity (e.g., dashboards, SaaS apps)
• Single Page Applications (SPA)
• Social media platforms

Choosing the Right Rendering Method

Feature	SSG	SSR	ISR	CSR
Performance	⭐⭐⭐⭐⭐	⭐⭐	⭐⭐⭐⭐	⭐⭐
SEO	⭐⭐⭐⭐⭐	⭐⭐⭐⭐	⭐⭐⭐⭐	⭐
Scalability	⭐⭐⭐⭐⭐	⭐⭐	⭐⭐⭐⭐	⭐⭐⭐
Dynamic Data	❌	⭐⭐⭐⭐	⭐⭐⭐	⭐⭐⭐⭐⭐

Conclusion

Each rendering method has its place in modern web development. If you want maximum speed and SEO, SSG or ISR is ideal. If your content changes frequently, SSR might be the better fit. For highly interactive web apps, CSR is often the way to go.