React.js Client-Side vs Server-Side vs Pre-rendering

With the Web constantly growing in size, you need fast load and refresh times for your website to beat the competition. Thankfully, new rendering methods help us optimize our sites for SEO and better UX. So we bring you an in-depth guide on Client-Side vs Server-Side vs Pre-Rendering to let you choose the best method for your website.

Client-Side Rendering


  • Fast Time to First Byte (TTFB)
  • Best for Web Applications with a lot of Dynamic Content
  • Less Page Reloads


  • Not good for SEO
  • Slow Time to Interactive
  • Not suitable for “static” sites designed for reading

Client-Side Rendering happens when your server returns a simple HTML document but with no content loaded in it. Instead, your browser executes the JavaScript code in this file and renders the UI dynamically.

As the first light-weight bare-bone HTML file downloads fast, the initial Time to First Byte is short. So, users can immediately see some activity. But, the JavaScript processing can take time and lead to a long Time to Interactive (the point at which users can start interacting with your web page).

The best part about client-side rendering is that there are no subsequent page reloads over the network after the initial load. Instead, the browser fetches all the UI changes dynamically in a piecewise manner. So, client-side rendering is ideal for web applications that involve lots of user interaction and dynamic UI changes.

Client-Side Rendering has been the go-to choice for developers in the past, with frameworks such as Angular and Ember.js supporting it. But, now, new developments in the React space provide us with more options to tweak our site for better performance.

Server-Side Rendering


  • Perfect for SEO
  • Best Suited for Static Sites with Readership as the primary goal
  • Decluttered and minimalist UI are the future of the web – Server Side Rendering is best for such interfaces


  • It needs a page to reload over the network for every subsequent request
  • Not suited for web applications with a lot of user interaction
  • High Hosting costs as it needs a more complex server
  • Prone to Database attacks as every request queries your back-end

Server-Side Rendering (SSR) was the old way of doing things (think PHP). Your server built an entire web page for every request and sent that over the network to the client machine. This was great for static sites or sites with less dynamic content. But, this approach fails with complex web applications that involve a lot of user interaction and dynamic content updates.

The main issue is the slow speed of fetching a page every time a user interacts with your website. Also, SSR provides attackers more chances to corrupt your database as every request queries your backend. Finally, you must bear the high costs of a robust hosting solution to provide good performance and uptime.

The good thing is that modern UI design moves toward a minimalist ethic. Users prefer simple interfaces with fewer components and pages with brevity being the key USP. So, developers need fewer dynamic reloads, especially for marketing or company websites. Server-side rendering is ideal for such use cases.

Web developers are always on the hunt for ways to optimize their sites and gain that crucial edge over their competitors. So, we now have optimized SSR with the ability to load the first page and then only get the necessary data with dynamic AJAX requests. Let’s look at the magic of React.

Universal or Isomorphic Apps – The Best of Both the Worlds


  • SEO friendly – Initial Server-Side Rendering helps Google Bot index your website easily
  • Fast Time to Paint and Time To Interactive
  • Combines the Best of Client-Side and Server-Side Rendering
  • The same code is used on server-side and client-side


  • Complex architecture
  • Security Loopholes as client-side authorization needs the download of a file with private data.

Universal Apps run both on the client and the server to provide fast load times and a better experience to visitors. In this method, server-side rendering fetches data and renders an initial page with custom content to send it quickly to the client. Note that this first page is semantically richer than the plain HTML file returned in pure client-side rendering. This meaningful first page helps Google crawler make sense of your site and is excellent for boosting your site's SEO. Also, it provides visitors with a better user experience.

Once the initial load completes, the client-side JavaScript fetches data and logic on the fly to update the page dynamically. Also, modern frameworks like React let you quickly write the same code for the client-side and server-side with built-in methods and features.

Universal apps provide another SEO benefit. As the server fetches data to load initial pages with custom content, you can fill up different routes with semantic content to help improve ranking and other metrics like shares and route-specific click-through rates.

Pre-Rendering – Do One Better: Serve a Static Front to your Dynamic Site


  • SEO friendly
  • Great for small-to-medium sites
  • Initial Load is static – Fast Time to Paint


  • Does not Provide User-Specific Content in the First Load
  • Need to specify different initial pages for different routes to the proxy – Impractical for large websites

Web Developers have come up with a clever way to make the solution used in universal apps even better using the Pre-rendering technique. Instead of serving a dynamic first page, pre-rendering loads a static pre-built initial page quickly.

As this static page loads super-fast, the user is hooked instantly. So, we can use this initial static skeleton to engage the user as we lead him into the full-blown dynamic page with specific content.

You can thus save pre-built static skeletons for your routes to deliver them quickly and then use React hydration to load dynamic content.

Pre-rendering helps you achieve great SEO results. You can optimize your pre-built static pages with meta-tags, styles, images, text and other SEO factors for crawlers to index them properly. And you don’t have to bear the costs of a full-blown SSR solution to do this.

The only bottleneck with pre-rendering is telling your proxy to deliver a different page for every route. This can become a lot of work for a large website running into hundreds of pages. But, for small and medium-sized websites, pre-rendering is a great way to boost SEO and traffic.


You no longer have to rely only on a pure client-side rendering method for your web applications. Exciting new developments like pre-rendering and isomorphic apps let you optimize sites for better SEO and UX performance. They build on the SEO muscle of SSR but combine it with creative hacks to let you get an edge over your competitors.


  • What is pre-rendering in SEO?

When we use pre-rendering for our sites, we deliver pre-built static HTML pages optimized for SEO to help crawlers index our sites better. So, we get better SEO results.

  • What are the benefits of pre-rendering for SEO?

Pre-rendering lets you optimize your website for search engines without bearing the enormous costs of a Server-side rendering solution.

  • What is pre-rendering in React?

You can use the react-snap and react-snapshot libraries to pre-render your content in React.

  • Which rendering method is best for my website?

Every rendering method is best suited for specific use cases. You should read our in-depth guide above on client-side vs server-side vs pre-rendering to find the best-fit method for your site.

Rachin Kapoor

Rachin Kapoor

Montreal, QC, Canada