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FixAEO
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Free Canonical Tag Checker

Paste a page's HTML. We'll find the canonical tag, validate it against the 4 common pitfalls, and cross-check og:url.

Paste page HTML

Source of one page

Right-click the page → View Source → copy the <head> section (or the whole HTML).

Paste your page's HTML on the left and we'll find the canonical tag, validate it, and cross-check against og:url.

What we check

The four most common canonical mistakes — flagged with a fix.

Tag presence + uniqueness

Exactly one rel='canonical' link in <head>. Zero canonicals or multiple canonicals both get flagged with concrete fixes.

Absolute vs relative

Canonical href should be a full https URL, not a relative path. We flag relative URLs and trailing query separators.

og:url cross-check

Social-share URL should match canonical. Mismatches cause split attribution across SEO, social, and AI surfaces.

Frequently asked questions

What is a canonical tag?
<link rel="canonical" href="..."> tells search engines and AI crawlers which version of a URL is the 'official' one when the same content exists at multiple URLs (with tracking params, mobile/desktop versions, http/https, etc.). Without it, crawlers split ranking signals across duplicates.
Why does canonical matter for AEO?
AI assistants pull the canonical when they cite a page. If your canonical points to the wrong URL — or to a competitor's URL by mistake — they cite that URL, not yours. Self-canonical mistakes are surprisingly common and silently leak attribution.
Can I have multiple canonical tags?
No. Google, Bing, and every AI crawler treat multiple canonicals as ambiguous. They may pick any of them or ignore all. Exactly one rel='canonical' link per page, inside <head>.
Should the canonical be absolute or relative?
Absolute (https://example.com/page). Google explicitly recommends absolute URLs. Relative URLs work in some crawlers but break when the page is fetched from a different base.
Why does og:url matter?
og:url is the canonical equivalent for social previews and many AI assistants. They should match. When they don't, you get split attribution — social shares cite one URL, AI assistants cite another.

Scanning the whole site?

The full FixAEO audit checks canonical tags + 9 other AEO signals across your entire site automatically.

Run a free AEO audit