SEO JS Checker | Chrome extension for JavaScript SEO audits

Reliable audits for JavaScript-rendered SEO

SEO JS Checker is a Chrome extension that helps you identify critical JavaScript-related SEO issues by comparing a page’s raw HTML with its rendered DOM. It inspects head elements, visible text, and links to highlight changes, missing tags, and other discrepancies caused by client‑side rendering.

Why SEO JS Checker?

Modern websites often rely on JavaScript to inject or modify critical HTML tags, from meta descriptions and canonical URLs to structured data and internal links. While convenient for development, this poses real risks for SEO, particularly if search engines don’t see the final rendered output the same way users do.

SEO JS Checker compares the raw HTML delivered by your server against the rendered DOM in your browser, so you can:

Audit internal and external links to catch SEO-critical omissions

Ensure your and meta tags load correctly

Verify canonical, preload and hreflang links survive JavaScript execution

Spot missing or altered headings, structured data, Open Graph and Twitter Card tags

Every difference is clearly labelled and grouped, with collapsible sections that make the report easy to scan.

Designed for real-world debugging

SEO JS Checker isn’t just a visual diff tool – it’s built to support practical debugging for dynamic sites:

Changed, missing, or added tags are automatically detected and flagged

Links are grouped by DOM section (e.g. nav, main, footer) and compared across states

Invalid anchor text (like embedded CSS or icon markup) is filtered out

Export reports as JSON, CSV or readable text files for documentation or sharing

Who it’s for

This tool is ideal for:

SEO consultants auditing JavaScript-heavy sites

Developers checking whether client-side rendering is causing SEO regressions

Technical teams verifying metadata consistency across frameworks like React, Vue, or Next.js

Features

Head-tag comparison: Detect differences, missing or unchanged values for:
- Page <title> and <meta name="description">
- <meta name="robots">
- <link rel="canonical">, <link rel="preload">, <link rel="preconnect">
- <link rel="alternate" hreflang>
- JSON-LD structured data
- Open Graph and Twitter Card metadata
Visible headings audit: Compare <h1> and <h2>, before and after rendering to catch dynamic content issues.
Link audit: Identify added, removed or changed internal and external links, grouped by section, with anchor-text sanitisation.
Interactive UI: Tabbed view with collapsible cards, summary badges and filter controls for quick insights.
Export & reporting: Copy to clipboard or download JSON, CSV, or TXT—raw and rendered data, full report or link lists.
Live badge icon: Toolbar badge shows the count of detected head-tag diffs in real time.

How it works

Click the SEO JS Checker icon in your Chrome toolbar.
Review the Head tab to compare raw vs. rendered metadata, headings and structured data.
Switch to Links to filter and inspect internal/external link changes.
Export your findings as JSON, CSV or TXT, or copy a plain-text report.

No setup required – everything runs in your browser, on any HTTP or HTTPS page.

Built with clarity and control

SEO JS Checker is intentionally minimal and transparent in its output. There are no external dependencies, no data collection, and no reliance on third-party APIs. Everything happens in-browser, using the page you’re viewing.

Developed by Adam King

This plugin was built by Adam King, a technical SEO consultant with over a two decades of experience helping websites navigate complex SEO issues, including JavaScript and indexing challenges.

Install now

You can get the extension from the Chrome Web Store.

Open Chrome and go to the Chrome Web Store.
Search for SEO JS Checker or visit https://chromewebstore.google.com/detail/seo-js-checker/mllilfpgoolaefgngamnamojfgpggglo.
Click Add to Chrome and confirm.
Navigate to any web page and click the extension icon to run your first audit!