Next.js SSR vs SSG: A Comprehensive Guide for Developers

Introduction

Next, The most common framework for React.js has completely changed the web development world through its game-changing rendering techniques — Server-Side Rendering (SSR) and Static Site Generation (SSG). Each approach has unique strengths and both can be useful depending on your applications requirements. Whether building a dynamic app with real-time data or creating a static content heavy site, knowing when to use what is essential for a solid architecture.

We will discuss what SSR and SSG are, advantages and disadvantages of both, and when to use either in the rest of this post. We will also see the new breath taking way to render your pages in a minimal operations API for you, Isr means Incremental Static Regeneration

What is Server-Side Rendering (SSR)?

Server-Side Rendering (SSR) refers to the generation of HTML on the server at runtime—that is, each time a user requests a page, the server dynamically fetches data and renders the content before sending it to the browser.

Key Features of SSR:

• Dynamic content rendering: Ideal for situations in which updates to data occur more often and changes to the displayed information are needed quickly, for example in application such as a dashboard or a news ticker.
• SEO-friendly: Further, the content is pre-rendered on the server. In such case Search Engines have an opportunity to index a fully loaded page thus improving SEO ranking.

In Next.js, SSR is done through a getServerSideProps function which works every time there is a request made. This helps keep the data fresh all the time, unfortunately, at the cost of performance, each new pager request involves a server call and a rerender.

Pros of SSR:

1. Real-time data: Each request put by a user is responded to with pages that are made using the most current data.
2. Improved SEO: All the elements of a fully rendered page are easier to be read by search engines.
3. Personalized Content: Every request results in a new page. So, it is suitable for complex pages containing information regarding individual interactions, such as profile or checkout pages.

Cons of SSR:

1. Slower Page Load Times: Every request involves processing on the server’s side and this makes page transitions slower than in pre-rendered pages.
2. Higher server load: The main downside therefore is that since each page request leads to a completely new server-side rendering. This may very become too much of a load for your servers especially if your website is a high-traffic one.

When to Use SSR:

• Dynamic apps: For apps that rely on real-time or user-specific data, like an e-commerce checkout or a live sports dashboard.
• SEO-driven pages: Pages that need to rank high on search engines but display dynamic content, like news articles or forums, benefit from SSR.

What is Static Site Generation (SSG)?

Static Site Generation (SSG) creates HTML pages at build time, meaning the content is rendered once during deployment and then served as static files. This makes it ideal for websites with content that doesn’t change often, such as blogs, marketing sites, or documentation.

SSG relies on the getStaticProps function in Next.js, which collects the necessary data at build time and pre-renders pages into static HTML. These files can be served through a Content Delivery Network (CDN), providing fast load times and low server strain.

Key Features of SSG:

• Pre-rendered content: Pages are generated ahead of time and can be cached for faster delivery.
• Highly scalable: Since static files can be served from a CDN, SSG is perfect for websites with large, global audiences.

Pros of SSG:

1. Lightning-fast performance: Static files load much quicker than SSR-generated pages since they don’t require server-side computation.
2. Low server load: With pre-rendered static pages, you can reduce server strain and easily scale your application.
3. Cost-Effective: By offloading requests to a CDN, you reduce server costs, especially for high-traffic applications.

Cons of SSG:

1. Stale data: Since the content is generated during build time, it won’t reflect real-time changes unless the site is rebuilt.
2. Limited to static content: It’s not suitable for apps that need to display frequently updated or personalized data.

When to Use SSG:

• Content-heavy websites: Blogs, documentation, or landing pages that don’t change often and prioritize fast loading times.
• Marketing and portfolio sites: Websites where performance and SEO are critical, but the content remains mostly static.

SSR vs SSG: Which One to Use?

Choosing between SSR and SSG largely depends on the nature of your project. Here’s a quick breakdown of when to use which:

• SSR is best for pages that require fresh content every time they’re accessed. For example, an e-commerce product page with real-time stock updates would benefit from SSR.
• SSG is ideal for pages where content doesn’t change often, like blogs or static landing pages. These sites can leverage pre-built HTML for faster page loads and superior performance.

If you want both, Next.js offers a hybrid approach, allowing you to use SSR for certain pages and SSG for others within the same project. This provides flexibility in designing your site’s architecture.

The Best of Both Worlds: Incremental Static Regeneration (ISR)

Next.js introduces Incremental Static Regeneration (ISR) to bridge the gap between SSR and SSG. With ISR, you can create static pages at build time but update them incrementally after the initial build. This means static pages can be refreshed at runtime, offering the flexibility of SSR without the performance trade-offs.

Benefits of ISR:

• Fresh content without rebuilding: Pages are updated after a certain interval, so you don’t need to rebuild the entire site for every minor change.
• Improved performance: Like SSG, most of the site is static and can be served quickly via CDNs, but specific pages get real-time updates.

ISR is particularly useful for sites with mostly static content but occasional updates, like an e-commerce store with product pages that need periodic price updates or stock status refreshes.

Final Thoughts

Next.js offers a versatility, from SSR to SSG to ISR, catering to different use cases and performance needs. Understanding the distinctions between these methods will empower you to make informed decisions for your project.

To recap:

• SSR is great for dynamic, frequently updated content that benefits from real-time data.
• SSG is perfect for static content that prioritizes performance and scalability.
• ISR blends the two, offering the best of both worlds for pages that need occasional updates without sacrificing speed.

By combining SSR, SSG, and ISR, Next.js ensures that developers have the flexibility to create high-performance web applications that cater to both SEO and user experience.

Got questions about Next.js or need help deciding which rendering method is right for your project? Let’s chat in the comments below!
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