Building a web application involves making a crucial decision: How should your pages be rendered? The choice between Static Site Generation (SSG), Server-Side Rendering (SSR), and Client-Side Rendering (CSR) can significantly impact performance, SEO, and user experience.
In this guide, we’ll break down SSG, SSR, and CSR, explaining how each works, their pros and cons, and when to use them.
What is Rendering?
Rendering is how a webpage turns raw code (HTML, CSS, JavaScript) into a fully displayed webpage for users. Different rendering strategies determine where and when this transformation happens.
The three main rendering strategies are:
- SSG (Static Site Generation) – Pre-generates pages at build time.
- SSR (Server-Side Rendering) – Renders pages on the server for each request.
- CSR (Client-Side Rendering) – Loads a minimal page, then uses JavaScript to fetch and render content on the client.
Each approach has its trade-offs in terms of speed, SEO, and interactivity.
Static Site Generation (SSG)
How It Works
With SSG, pages are generated at build time and served as static HTML files. When a user visits the site, the content is instantly available.
- At build time, the system pre-renders all pages.
- The static files are uploaded to a Content Delivery Network (CDN).
- Users get a fully-rendered page instantly from the nearest CDN.
Performance Impact
- Blazing fast load times (because files are served from a CDN).
- Best for SEO (fully rendered pages are available immediately).
- Scales efficiently (no database or backend calls per request).
- Not ideal for real-time updates (requires rebuilding for content changes).
When to Use SSG
- Marketing websites, blogs, and documentation.
- E-commerce product pages that don’t update frequently.
- Portfolio websites with pre-defined content.
Example Use Case
A personal blog is a great use case for SSG. Blog posts don’t change frequently, so pre-rendering them at build time ensures fast loading and great SEO.
Server-Side Rendering (SSR)
How It Works
With SSR, pages are generated on-demand, at request time.
- A user requests a page.
- The server fetches data and renders the page.
- The complete HTML page is sent to the browser.
Performance Impact
- Fresh, up-to-date content on every request.
- Better for dynamic pages than SSG (no need to rebuild).
- Good for SEO (search engines get fully-rendered pages).
- Slower initial load (server must process every request).
- Higher server costs (requires backend processing per visit).
When to Use SSR
- Dynamic dashboards with user-specific content.
- E-commerce sites with real-time stock updates.
- News websites where articles change frequently.
Example Use Case
An e-commerce product page that needs to display real-time inventory and pricing is an ideal use case for SSR.
Client-Side Rendering (CSR)
How It Works
With CSR, the initial HTML is minimal, and JavaScript loads the content dynamically in the browser.
- The user visits the page.
- The page loads a basic shell with no content.
- JavaScript fetches and renders data after the page loads.
Performance Impact
- Faster initial response (lighter server load).
- Better for highly interactive applications.
- Reduces server-side processing cost.
- Slower for SEO (content loads asynchronously).
- Poorer experience for slow network users (requires JavaScript execution).
When to Use CSR
- Single Page Applications (SPAs) like React and Vue apps.
- User dashboards that rely on frequent client-side updates.
- Chat applications and real-time collaboration tools.
Example Use Case
A real-time chat application benefits from CSR since content is constantly changing and doesn’t need to be pre-rendered.
How Rendering Choices Impact Performance
- SSG is the fastest because files are served from a CDN with no additional processing.
- SSR adds processing time since the server generates pages on demand.
- CSR delays content display as JavaScript needs to fetch and render it dynamically.
For best performance, many modern frameworks use a hybrid approach—combining SSG, SSR, and CSR where appropriate.
Additional Resources
Final Thoughts
Understanding SSG, SSR, and CSR is crucial for optimizing web performance, SEO, and user experience. There is no one-size-fits-all solution—choosing the right rendering strategy depends on your use case.
- SSG is best for fast, static content.
- SSR is great for real-time updates with SEO.
- CSR is ideal for highly interactive applications.
Many modern applications combine all three to create hybrid solutions that balance speed, scalability, and interactivity.