JavaScript rendering and server-side rendering
Also called: client-side rendering, JavaScript SEO, SSR
Definition
Client-side JavaScript rendering means sending an almost empty page that JavaScript fills in once it loads in the visitor's browser. It's common with apps built in React, Vue or Angular without any special setup. Server-side rendering, or SSR, sends a page that's already filled in.
Google can run JavaScript, with a delay. Most AI crawlers don't: according to the Vercel and MERJ study, GPTBot, ClaudeBot and PerplexityBot only read the raw HTML. A site rendered in the browser can therefore be invisible to them, even if it displays perfectly.
Example
A pricing page that loads its prices with JavaScript after display shows prices to the visitor, but an empty block to ClaudeBot. The AI then answers with prices found elsewhere, sometimes outdated.
What it means for your AI visibility
Test what crawlers receive: if your main text isn't in the raw HTML, move your key pages to server-side rendering or pre-rendering. No robots.txt setting makes up for this problem.
Free toolAI crawler simulatorSee your page the way GPTBot, ClaudeBot and PerplexityBot see it.Related terms
- AI crawlerAn AI crawler is a bot that browses the web on behalf of an AI company, to train its models or feed its answers.
- GPTBotGPTBot is the OpenAI crawler that collects pages to train its models. OpenAI uses other crawlers for ChatGPT's search.
- Citable contentCitable content is written so AI can reuse it as is: one idea per paragraph, precise facts, a direct answer to a question.
- SEOSEO optimizes a site for traditional search engines. It is still the foundation of GEO, but it's no longer enough to get recommended by AI.
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