JavaScript SEO checker
Can search engines and AI crawlers see your content without running JavaScript? SiteScope reads your pages as raw HTML and shows what is missing.
Free. No sign-up. Crawls up to 300 pages per audit.
Why raw HTML matters
Google renders JavaScript, but rendering can be delayed, and it fails when scripts error or are blocked by robots.txt. Many other crawlers do not render at all: a December 2024 server-log study by Vercel and MERJ found that the major AI crawlers, including GPTBot, ClaudeBot and PerplexityBot, do not execute JavaScript.
Common React SEO problems
- Empty shell. The server sends a page with only a root div; the text appears after JavaScript runs. SiteScope flags pages under 200 words of raw text.
- Links as click handlers. Navigation built with onClick instead of <a href> is invisible to crawlers, so deeper pages are never found. Compare the pages crawled with the pages you expect.
- Titles set in the browser. Titles and meta descriptions added by scripts are missing from raw HTML. SiteScope reports missing and duplicate tags.
- Canonical tags added late. A canonical tag inserted by JavaScript may be ignored.
Client-side rendering vs server-side rendering for SEO
With server-side rendering or static generation (for example Next.js or Astro), the HTML already contains the content and links, so every crawler can read them. Client-side rendering leaves that work to the crawler. If SiteScope finds very little text or very few pages on a JavaScript site, server-render the key pages first.
How Google renders JavaScript
Googlebot first fetches the HTML, queues the page for rendering, then runs it in an evergreen Chromium and indexes the rendered result. Google's own guide, Understand JavaScript SEO Basics, explains the steps.