Server-Side Rendering vs Static Site Generation in Next.js: When to Use Each,

As web developers, one of the most crucial decisions we make is how to render the content of our web pages. Next.js, a powerful React framework, offers two primary rendering methods: Server-Side Rendering (SSR) and Static Site Generation (SSG). Both methods have distinct advantages, and knowing when to use each is key to optimizing performance, SEO, and user experience for your web applications.

In this post, we'll explore SSR and SSG, compare them in terms of performance, SEO, and user experience, and help you understand when it's best to use each technique in your Next.js projects.

What is Server-Side Rendering (SSR)?

Server-Side Rendering (SSR) is the process of generating HTML for a page on the server for each user request. When a user visits a page, the server dynamically renders the content based on the data fetched in real-time and sends the fully-rendered HTML to the client. This approach allows for highly dynamic pages with content that can change on every request.

How It Works:

In Next.js, SSR is achieved using the getServerSideProps function. This function runs on the server every time a page is requested, fetching the data and rendering the page with the latest information.

Benefits of SSR:

Real-Time Data: Because the page is generated on the server for each request, it can fetch the latest data, making it ideal for applications that rely on dynamic, real-time content.

Personalization: SSR allows for user-specific content, such as dashboards or personalized recommendations, based on real-time user data.

SEO-Friendly: Search engines can easily crawl and index the fully-rendered HTML, making SSR a great choice for SEO.

When to Use SSR:

Dynamic Content: SSR is perfect when your content changes frequently, like user dashboards or live data.

Personalized Experiences: For apps that require user-specific data, such as e-commerce websites with tailored product recommendations.

SEO Optimization: When SEO is crucial for content that needs to be up-to-date for every user, such as news or social media feeds.

What is Static Site Generation (SSG)?

Static Site Generation (SSG) is the process of pre-generating HTML files at build time, which are then served as static files to users. This approach works well for pages that don't require real-time data, offering fast loading times and excellent scalability.

How It Works:

In Next.js, SSG is handled using the getStaticProps function, which runs at build time to fetch the necessary data and generate the static HTML for each page. These pages are then served directly from the CDN, ensuring lightning-fast load times.

Benefits of SSG:

Performance: Static pages are served directly from a CDN, resulting in faster load times and improved overall performance.

Scalability: Static files are lightweight and can handle a large number of users without taxing the server.

Lower Costs: Since static files don’t require server-side processing for each request, hosting costs are typically lower compared to SSR.

When to Use SSG:

Content That Doesn’t Change Often: If your pages have content that is static or updated infrequently (like blogs, documentation, or marketing pages), SSG is a great choice.

Better Performance: SSG is ideal for performance-focused websites, as static files load almost instantly.

SEO-Friendly: Like SSR, SSG also generates fully-rendered pages that are easy for search engines to crawl and index.

When to Use Server-Side Rendering (SSR)

SSR is ideal for applications that require real-time, dynamic content. Here are some scenarios where SSR shines:

Real-Time Data: When your website or app fetches data that frequently changes, such as stock prices, sports scores, or news updates.

User-Specific Content: Websites that require user login or personalization, such as dashboards, e-commerce sites, and social networks.

Dynamic Content for SEO: When SEO is a priority for content that must be rendered dynamically, such as personalized product pages or live data.

**When to Use Static Site Generation (SSG)

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SSG is the best choice when your content is largely static or updated only occasionally. Consider using SSG for:

**Marketing Websites: **If you’re building a company homepage, landing page, or marketing site, where the content doesn’t change often, SSG provides optimal performance and scalability.

Blogs: Blogs, portfolios, and documentation sites where content updates are infrequent are perfect candidates for SSG.

E-commerce: For product listings that rarely change, using SSG for the main product pages can result in faster loading times and improved SEO.

Combining SSR and SSG in Next.js

One of the key strengths of Next.js is its ability to use both SSR and SSG in the same project. This means you can use SSG for static pages that don’t need to be updated frequently (such as blogs or marketing pages), and SSR for pages that need to fetch real-time data (like user dashboards or e-commerce product pages).

Next.js allows you to define which pages use SSR and which use SSG with the getStaticProps and getServerSideProps functions. This flexibility allows you to optimize each page according to its specific needs.

Conclusion

Both Server-Side Rendering (SSR) and Static Site Generation (SSG) have their place in Next.js projects, and understanding when to use each can significantly enhance your website's performance, SEO, and user experience.

Use SSR when your content is dynamic and requires real-time updates or personalization.

Use SSG when your content is static or updated infrequently, focusing on fast load times and scalability.

Next.js gives you the flexibility to combine both approaches, ensuring you can use the right tool for the right job. So, whether you're building a high-performance blog or a dynamic e-commerce site, understanding SSR and SSG will help you deliver the best possible experience for your users.