Server-Side Rendering (SSR)
Server-side rendering is generating a page's HTML on the server so its content is present in the initial response, before any JavaScript runs in the browser.
Many AI crawlers do not execute JavaScript. A page whose content is assembled client-side may therefore be seen as an empty shell — the markup arrives, the substance never does.
This is among the most common and most severe AEO failures, because it is invisible in a browser. The page looks perfect to a human and is blank to the machine.
Why it matters
If your content is not in the served HTML, no amount of quality or structured data helps. It is the first thing worth checking and the most consequential thing to get wrong.
An example
A product page built as a single-page application sends the browser an almost empty HTML document and a JavaScript bundle; the product details appear only after the script runs. A person sees a complete page. A crawler that does not run JavaScript receives the empty document and records a page with no product on it.
Common mistakes
- Checking only in a browser, which always runs JavaScript and hides the problem.
- Server-rendering the layout but loading the actual content client-side afterwards.
Questions
- Do AI crawlers render JavaScript?
- Many do not. Googlebot renders JavaScript, though on a delay, but most AI crawlers work with the HTML the server returns. Content that exists only after scripts run may be invisible to them.
- How do I check what a crawler sees?
- Fetch the page without running JavaScript — viewing the raw page source rather than the inspected DOM — and check whether the main content is present. If the words you care about are missing from the source, a non-rendering crawler cannot see them.