5 free tools to check what search engines and AI crawlers see

JavaScript websites need more than one kind of crawler check.

Sometimes you need to inspect one page as several bots. Sometimes you need to compare raw and rendered HTML. Sometimes the problem is not rendering at all, but robots rules, missing metadata, or inconsistent templates across a sitemap.

The right free tool depends on the question you are trying to answer.

Quick answer

Use the Bot View Checker for one page, Raw HTML vs Rendered HTML for rendering gaps, JavaScript SEO Score for a technical summary, Robots.txt and llms.txt Analyzer for discovery files, and the Bulk Crawler Readability Checker for several pages.

The five-tool workflow

All five tools diagnose technical visibility. They do not guarantee rankings, indexing, traffic, or AI mentions.

1. Bot View Checker

Use the Bot View Checker when you want to know what crawler-style requests receive from one important URL.

It is the best starting point when:

• the browser looks complete
• view-source looks suspiciously thin
• different bots may receive different responses
• you want a quick check before changing infrastructure

The result focuses on crawler access, readable text, page metadata, headings, and bot-specific responses.

Use it for a homepage, pricing page, key landing page, or any URL already showing indexing or preview problems.

2. Raw HTML vs Rendered HTML

Use the Raw HTML vs Rendered HTML Comparer when you need to prove that JavaScript adds important content after the initial response.

This comparison is especially useful for React, Vite, Vue, Lovable, Bolt, Base44, and similar client-rendered sites.

Look for:

• much more text after rendering
• headings that appear only after JavaScript
• metadata differences
• internal links missing from raw HTML
• an initial #root or #app shell

A large gap may indicate that some crawlers receive less content than visitors.

3. JavaScript SEO Score

Use the JavaScript SEO Score when you want a compact technical summary for one page.

The score combines several signals:

• crawler access
• readable text
• title and meta description
• heading presence
• obvious app-shell behavior

The score is useful for prioritization, not as a universal SEO grade. A high score does not mean the content will rank. A low score helps identify what to inspect first.

4. Robots.txt and llms.txt Analyzer

Use the Robots.txt and llms.txt Analyzer for site-level discovery and access files.

It checks whether:

• robots.txt is available
• broad crawler rules appear open or blocked
• sitemap directives exist
• llms.txt is available
• llms.txt has a useful Markdown heading and links

This tool answers a different question from the page checkers. A page can contain excellent HTML and still be blocked by crawler instructions. Conversely, an open robots.txt file does not prove that page HTML is readable.

5. Bulk Crawler Readability Checker

Use the Bulk Crawler Readability Checker when you need a first pass across several pages.

Enter an XML sitemap or paste up to 10 important URLs. The result highlights pages with:

• thin raw text
• missing titles, descriptions, or H1 headings
• JavaScript app-shell signals
• errors or unexpected response statuses

The bulk checker is most useful before launch, after a redesign, or when several route templates need review.

For the complete workflow, read How to audit crawler readability across an XML sitemap.

Chrome extension for checks while browsing

The Prerender Buddy Chrome extension provides another entry point for quick checks while reviewing your own website.

Use it when you are moving through pages in the browser and want a fast score without opening the tools hub each time. Open the full web checker when a page needs more detail.

Which tool should you start with?

For one suspicious page, start with the Bot View Checker.

For a JavaScript-rendering question, use Raw HTML vs Rendered HTML.

For several pages, start with the Bulk Crawler Readability Checker and move suspicious URLs into the single-page tools.

For crawler rules and discovery files, use the Robots.txt and llms.txt Analyzer.

If you are unsure, open the free crawler tools hub and follow the recommended order.

What to do after finding a problem

First identify the type of problem:

• access or HTTP error
• robots blocking
• missing metadata
• hostname inconsistency
• thin raw HTML
• large raw-versus-rendered gap

Content and metadata problems should be fixed at their source. Hostname and access problems need routing or DNS corrections. If crawlers receive a thin JavaScript shell while the rendered page contains the real content, SSR, static generation, or a crawler rendering layer may be appropriate.

The tools are the diagnosis step. The correct fix depends on what the results actually show.

Final recap

5 free tools to check what search engines and AI crawlers see comes down to what search engines and AI crawlers actually receive from your site.

Prerender Buddy does not guarantee rankings or AI citations. It helps with one specific technical problem: making sure crawlers receive readable rendered HTML instead of a thin JavaScript shell.

The first step is to check what bots see.

Check your website

Open the free crawler tools hub to test whether the site sends readable HTML to search engines and AI crawlers.