SEO Tools

HTML head diff.

Paste the staging and production source of a page. The tool reads each head, compares the tags that affect search, and ranks the differences so a stray noindex or a canonical pointing at the wrong host is at the top.

Inputs

Result

Paste the staging and production head, then press Compare.

How the head diff works

Each input is cut down to its <head> (or used whole if no head tag is present) and read with a plain text parser. It collects the title, every meta tag by name, property or http-equiv, rel="canonical" links, rel="alternate" hreflang links, and the @type values inside application/ld+json blocks. The two sides are then compared field by field and each difference is ranked.

Worked example

Staging head: <meta name="robots" content="noindex, nofollow"> and <link rel="canonical" href="https://staging.example.com/pricing/">. Production head: <meta name="robots" content="index, follow"> and a canonical of https://example.com/pricing/. Paste staging as the old side and production as the new side and the tool reports a changed canonical host and a removed noindex, nofollow. Reverse the sides to test a release candidate: if the new side gains noindex or a staging canonical, both show as SEO-critical.

How differences are ranked

SEO-critical: the new side adds noindex, none or nofollow in a robots, googlebot or bingbot meta tag; the canonical is missing, differs, points to another host, or appears more than once.
Review: title or meta description changed, a hreflang alternate removed or re-pointed, a social tag (Open Graph or Twitter) added or removed, JSON-LD types missing or invalid JSON.
Info: other meta tags, added hreflang or schema types, charset differences.

This compares the tags as written in the pasted source. It does not render JavaScript, follow redirects, read HTTP headers such as X-Robots-Tag, or confirm what Google indexed. Use Search Console URL Inspection for that. Canonical and hreflang URLs are compared as text, so a trailing-slash difference counts as a mismatch.

Sources

Google guidance reviewed September 30, 2026.

HTML head diff FAQ

Why diff staging against production?

Staging sites are often set to noindex and use their own canonical host. If that head ships to production, pages can drop out of search. A diff before launch catches it.

Which side is "old" and which is "new"?

Either way works. Put the version you trust on the left and the version you are about to ship on the right, because critical flags describe what the right side adds or breaks.

Does it fetch URLs?

No. Browsers block reliable cross-origin fetching, so paste the source. View Source or curl output both work.

Can it see an X-Robots-Tag header?

No. That is an HTTP header, not part of the HTML. Check response headers separately.

Is pasted HTML uploaded?

No. Parsing runs locally in your browser and pasted markup is never loaded, so embedded resource URLs are not requested. The page itself still uses the site's analytics and advertising services.