Raw vs rendered HTML checker
Your title, canonical, robots directive and internal links only count if a crawler can see them without running JavaScript. Paste one URL and this free checker compares the raw HTML your server sends against the rendered page, so you can see what shows up late.
This tool checks once.Page Monitoring keeps checking.
It checks on a schedule and alerts you the moment the result changes, so you never have to remember to run this again. Ask Theo, the AI assistant in the app, and it explains any finding in plain words.
The same check on every page you visit
In the free VitalSentinel SEO Extension for Chrome, one click shows the raw HTML next to the rendered page, with every field JavaScript changes marked, for the page you have open.
- Free
- No account needed
- One click
What it checks
- Fetches the HTML your server sends, then loads the same URL in a real browser and reads the page the moment loading finishes
- Puts nine signals side by side: word count, title, meta description, canonical, H1, meta robots, internal links, JSON-LD blocks and Open Graph tags
- Leads with the costly cases, such as a noindex or a canonical that appears only after rendering
- Reads X-Robots-Tag from the server response, and lists the markup lines one version has and the other does not, side by side
What it does not
- It reads the page the moment loading finishes, with no extra wait. Content that arrives later on a timer, on scroll, after a click or behind a login is not compared
- It identifies itself as VitalSentinel Free Tools Bot, not Googlebot, so it is not a Googlebot simulation
- Internal links, JSON-LD blocks and Open Graph tags are compared by count, not content, so swapping one og:image URL for another reads as a match. twitter: card tags are not compared at all
- A counted signal has to change by at least a quarter to affect the verdict, so 800 words against 900 is listed as a minor difference. Each version is read up to the first 512 KB
Questions
Does Google index content that only appears after JavaScript runs?
Yes, but later: Google renders in a second pass on a queue of its own. And most AI crawlers plus every social preview bot, including Facebook, LinkedIn and Slack, never render at all.
Does this tell me what Googlebot sees?
It shows what a browser sees, and what a crawler that does not run JavaScript sees. It is not a Googlebot simulation, since we identify honestly as VitalSentinel Free Tools Bot. For one specific URL, use URL Inspection in Google Search Console.
My Open Graph tags come from a tag manager. Will link previews work?
No. No social preview crawler runs JavaScript, so it reads the served HTML, finds no og:title or og:image, and falls back to whatever the raw markup does contain – usually the plain title tag and no image at all.
Those tags have to be in the initial HTML for a preview to look the way you designed it.
Why is my page empty in view source but fine in the browser?
The server is sending an empty shell and JavaScript is writing the content into it. This comparison shows the gap as a word count, server HTML against what the browser ends up with.
If the server side is close to zero, everything that does not run JavaScript sees an empty page, and server-side rendering or prerendering for that page is what closes the gap.
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