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AMP HTML Link Tag on Pages With AMP Versions

Issue No: 134

Category: Link Rel Tags Issue type: Warning Priority: STANDARD

Description​

Pages that have an Accelerated Mobile Pages (AMP) counterpart should declare a <link rel="amphtml"> tag in the canonical page <head> pointing to the AMP version, so that search engines can discover and serve the faster mobile variant in applicable search contexts.

How do we capture it​

Inside HTML <head> on the canonical (non-AMP) page:

<link rel="amphtml" href="https://example.com/article/?amp=1">

The AMP page itself should contain a corresponding canonical back-reference:

<!-- On the AMP page -->
<link rel="canonical" href="https://example.com/article/">
  1. Issues an HTTP GET to the target URL.
  2. Reads raw response bytes without JavaScript execution.
  3. Scans the <head> block for all <link> tags.
  4. Searches for a tag where rel equals amphtml.
  5. Extracts the href attribute value.
  6. Issues a secondary HTTP GET to the AMP href URL.
  7. Records the HTTP status code of the AMP page response.
  8. Checks whether the AMP href is a valid absolute URL.

The crawler validates:

  • Whether a <link rel="amphtml"> tag exists in the head.
  • Whether the href is a valid, non-empty absolute URL.
  • Whether the AMP page URL returns HTTP 200.

What to store​

FieldTypeComment
has_amphtml_linkBOOLEANWhether an amphtml link tag is declared in the page head
amphtml_hrefTEXTThe href value of the amphtml link tag
amphtml_href_statusINTHTTP status code returned when fetching the AMP page URL
amphtml_is_absolute_urlBOOLEANWhether the amphtml href is a valid absolute URL

Condition for trigger​

The following trigger rules evaluate AMP HTML link tag validity and reachability.

  • Trigger Rule 1: Missing AMP HTML Link Tag

    • Target Field: has_amphtml_link
    • Evaluation Logic: = FALSE
    • Severity: SUGGESTION
    • Diagnostic Message: "No AMP counterpart link tag was found. If this page has an AMP version, add a <link rel='amphtml'> tag so search engines can discover and serve the faster mobile variant."

  • Trigger Rule 2: AMP Page URL Not Reachable

    • Target Field: amphtml_href_status
    • Evaluation Logic: NOT IN (200, 201, 204)
    • Severity: WARNING
    • Diagnostic Message: "The declared AMP page URL does not return a valid HTTP response. Search engines cannot access the AMP version and will fall back to the canonical page."

  • Trigger Rule 3: AMP href Is Not an Absolute URL

    • Target Field: amphtml_is_absolute_url
    • Evaluation Logic: = FALSE
    • Severity: STANDARD
    • Diagnostic Message: "The amphtml href value is not an absolute URL. Google requires the amphtml href to be a fully qualified URL including scheme and domain."

Sources​

Long description​

AMP (Accelerated Mobile Pages) is an open-source framework that creates stripped-down, fast-loading versions of web pages optimized for mobile delivery by Google's cache infrastructure. When a site has both a canonical page and an AMP version, the two pages must be linked to each other so search engines understand their relationship.

On the canonical page:

<link rel="amphtml" href="https://example.com/article/?amp=1">

On the AMP page (back-reference):

<link rel="canonical" href="https://example.com/article/">

This pairing tells Google:

  • The canonical is the full-featured version.
  • The AMP URL is the mobile-optimized counterpart.
  • Both represent the same content.

Without the amphtml link:

  • Google may not discover the AMP version during crawling.
  • The AMP page may not appear in AMP-eligible search results (Top Stories carousel, AMP badge).
  • Content freshness signals between canonical and AMP versions may diverge.

Without the canonical back-reference on the AMP page:

  • Google may treat the AMP and canonical pages as duplicate content.
  • AMP page may be indexed independently without connecting to the canonical.

Common failure scenarios:

  • amphtml link missing on canonical page: The AMP page exists but the canonical page never declares the <link rel="amphtml"> tag. Search engines cannot discover the AMP version through HTML inspection alone.
  • AMP URL returns 404: The tag is present but the AMP page was deleted or moved, causing the HTTP fetch to return a non-2xx status code.
  • Relative URL instead of absolute: The amphtml href uses a root-relative path instead of a fully qualified absolute URL. Google's AMP guidelines require the href to include scheme and domain.
  • AMP page blocked by robots.txt: The AMP URL exists and returns 200 but is blocked by Disallow rules in robots.txt, preventing search engines from crawling it.

How to Fix​

Add the AMP link tag to the canonical page <head>:

<link rel="amphtml" href="https://example.com/article/?amp=1">

And ensure the AMP page links back to the canonical:

<!-- On the AMP page -->
<link rel="canonical" href="https://example.com/article/">

Requirements:

  • The amphtml href must be a fully qualified absolute URL (including https://).
  • The AMP page URL must return HTTP 200.
  • The AMP page must not be blocked by robots.txt.
  • If the AMP version no longer exists, remove the <link rel="amphtml"> tag from the canonical page entirely.