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CRAWLING, RENDERING & INDEXING

Rendering in SEO: what it means and how it works

Running a page’s code to build the final content a search engine indexes.

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All glossary terms
  • Intermediate level
  • 3 primary sources
  • Reviewed 29 October 2026
At a glanceSEO glossary
  • TopicCrawling, rendering & indexingAlso in Technical SEO, Core Web Vitals & performance
  • LevelIntermediateAssumes the basics of how search works
  • Sources3 primary sourcesGoogle Search Central, Search Console Help
  • Reviewed29 October 2026Re-checked every 12 months
On this page
  1. Quick definition
  2. Why it matters
  3. How it works
  4. Example
  5. How to check it
  6. Common mistakes
  7. Related concepts
  8. Check it on your site
  9. Keep learning
  10. Sources and review

Quick definition

Rendering is running a page’s HTML, CSS and JavaScript to produce the page a visitor actually sees. Google renders pages in a recent version of Chromium before indexing them, so content that only exists after JavaScript runs can still be indexed, but later and less reliably than content in the initial HTML.

Why it matters

The HTML a server sends and the page a browser shows can be very different. On a site built with client-side JavaScript, the initial response may contain an empty container and a script tag. If a search engine indexes only that response, the product names, prices and links are missing.

Rendering also matters beyond Google. Many crawlers, including many AI crawlers, fetch HTML without executing JavaScript. Content that depends on scripts may be invisible to them.

How it works

Google processes JavaScript pages in three phases: crawling, rendering and indexing. After fetching a URL, Google queues it for rendering; its Web Rendering Service runs the page in headless Chromium, and links and content in the rendered HTML go on to indexing. The rendering step adds time and can fail if scripts are blocked, time out or depend on user interaction.

ApproachWhat the first response containsSearch implications
Server-side rendering (SSR)Complete HTML for the pageContent and links are available at crawl time, to every crawler
Static generationPre-built complete HTMLSame as SSR, cached; content is as fresh as the last build
Client-side rendering (CSR)A shell; JavaScript builds the contentDepends on the crawler executing scripts successfully
Hydration (SSR + CSR)Complete HTML, made interactive by JavaScriptUsually the safest modern default

Google has described dynamic rendering, serving pre-rendered HTML only to bots, as a workaround rather than a recommended long-term solution.

Example

A property portal loads listing details with a script after the page shell arrives. The raw HTML of /homes/2-bedroom-apartment-kilimani/ contains the site header and a loading spinner. Google’s URL Inspection screenshot shows the full listing, so Google can render it, but a social preview bot and several AI crawlers see only the spinner. Moving the listing details into the server response fixes all of them at once.

How to check it

  1. Compare the page source (the raw HTML response) with the rendered DOM in your browser’s developer tools. Note anything important that exists only in the rendered version.
  2. Use URL Inspection in Search Console and view the tested page’s rendered HTML and screenshot.
  3. Check that resources needed for rendering (scripts, APIs, CSS) are not blocked by robots.txt.
  4. Make sure links are real <a href> elements; Google does not follow links that only exist as click handlers.

No change is needed when the content and links you care about are already in the initial HTML.

Common mistakes and misconceptions

  • Myth Google cannot index JavaScript.

    In fact Google renders JavaScript with an evergreen Chromium. The risks are delay, failures and other crawlers that do not render, not an outright inability.

  • Myth If it looks right in my browser, search engines see the same thing.

    In fact Your browser has your cookies, consent choices, location and unlimited time. A crawler may be blocked, time out, or skip scripts entirely.

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Keep learning

GuideHow indexing really worksDiscovery, crawling, inspection and indexing are separate steps, with separate evidence.Read the guide

Sources and review

Written and maintained by Ndovu SEO Labs. First published 29 October 2026. Facts last checked against the sources above on 29 October 2026. How we write and review the glossary.