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What is client-side rendering?

Client-side rendering is a way of building web pages where the visitor's browser runs JavaScript to create the page's content, instead of the server sending finished HTML. A crawler that does not run the script can see a nearly empty page.

Cited from the66th.com/glossary/client-side-rendering

Liam Lytton Founder, The 66th Published 3 November 2026Updated 3 November 2026

How client-side rendering works

With server-side rendering, the server sends a finished page: the HTML, the code browsers read, already holds the headings and text. With client-side rendering, the server sends a short HTML file and a JavaScript program. The browser runs the program, and the program writes the content into the page. web.dev defines client-side rendering as rendering an app in a browser, using JavaScript to modify the DOM, the browser's live model of the page.

You can see the difference with View Source in any browser. It shows the HTML the server sent, before any script runs.

<!doctype html>
<html lang="en">
  <head>
    <title>Plumber in Calgary | Example Plumbing</title>
    <script type="module" src="/assets/app.js"></script>
  </head>
  <body>
    <div id="root"></div>
  </body>
</html>
What View Source shows for a client-side rendered page on example.com. The services, service area and phone number appear only after app.js runs. Illustrative.

Why Google and AI tools care

Google processes JavaScript pages in three phases, crawling, rendering and indexing, and its JavaScript SEO guide says a page can wait in the rendering queue for a few seconds or longer. The same guide calls server-side rendering or pre-rendering still a great idea, because it makes a site faster for users and crawlers, and because not all bots can run JavaScript.

Google's guide to generative AI features says Google can process content within JavaScript as long as it isn't blocked, and that SEO on a site built with JavaScript frameworks is generally more complex than on other kinds of sites.

What it means for your business

If your pages are client-side rendered, Google may still read them after rendering, but any bot that cannot run JavaScript reads only the empty shell. We see this most on sites built with AI website builders that run on React and Vite (two JavaScript tools) with no server-side rendering set up.

A site that already sends its text in the HTML has nothing to change here. Rendering checks are part of our technical SEO services.

Common mistakes

  • Checking the site only in a browser. The browser runs the script, so the page looks complete; View Source shows what a crawler receives first.
  • Blocking JavaScript or data files in robots.txt, the file that tells crawlers which addresses to skip. Google's AI features guide says Google can process JavaScript content as long as it isn't blocked.
  • Loading the main text only after a click or a scroll. Put the content a buyer needs in the HTML the server sends.
IndexingGoogle storing a page so it can appear in results. A page that is not indexed cannot rank for anything. Core Web VitalsGoogle's three measures of how a page loads, responds and holds still, taken from real Chrome visits. AI crawlersThe bots AI companies send to read web pages for model training, AI search answers or a user's request, such as OpenAI's GPTBot. Site migrationMoving a site to a new platform, host or set of addresses. Each old address needs a redirect to its match, or visitors hit errors.

Sources: web.dev, Rendering on the web, 5 January 2026; Google Search Central, Understand the JavaScript SEO basics, 4 March 2026; Google Search Central, Google's guide to optimizing for generative AI features on Google Search, 10 July 2026.

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