What is rendering in SEO?

Rendering, explained

Google's JavaScript SEO guide describes three phases: crawling, rendering and indexing. Googlebot first fetches the URL and parses the raw HTML for links. Then pages that return 200 are queued for rendering, unless a robots meta tag says not to index them. A headless, evergreen version of Chromium executes the JavaScript, and Google indexes the rendered HTML.

The gap between crawling and rendering is the part to understand. Google says a page may wait in the render queue for a few seconds, but it can take longer. Anything that only exists after rendering, like client-side-loaded text, links built by script or a noindex removed by JavaScript, depends on that second step. Content in the initial HTML is seen immediately.

Rendering can also fail or differ from what users see. Scripts blocked by robots.txt can't run. API calls that time out leave empty sections. Content that loads only after a click or scroll never appears, because Googlebot doesn't interact with pages. And other crawlers, including many AI crawlers, don't execute JavaScript at all, so they only see the raw HTML.

To see what Google rendered, use URL Inspection in Search Console and view the tested page's HTML and screenshot. If important text or links are missing there, they're missing for Google. The simplest way to avoid rendering risk is to send the important content in the HTML itself, through server-side rendering or static generation, and use JavaScript for interaction on top.

Why it matters for founders

Many startup sites are built as JavaScript apps. If your key content only appears after rendering, you depend on Google's queue and lose crawlers that don't run JavaScript at all.

Example

Your pricing table is fetched from an API after page load. URL Inspection's rendered HTML shows the table, but curl shows an empty div. You render the table on the server so every crawler sees it.

Common mistakes

• Blocking JavaScript or CSS files in robots.txt.
• Loading main content only after user interaction.
• Assuming every crawler renders JavaScript like Googlebot.
• Testing only in your own browser instead of URL Inspection.