Rule Details

Linking out to authoritative external sources is a mark of quality content. It supports your claims, helps users verify information, and reinforces the same trust expectations covered in content citations and Google's outbound-link qualification guidance (opens in new tab).

Code Examples

❌ Avoid — unsupported claim with no source

<p>Studies show that 70% of websites have accessibility issues.</p>
<!-- No link to the study; readers cannot verify -->

❌ Avoid — external link missing security attributes

<a href="https://example.com/research">View the research</a>
<!-- Missing rel="noopener noreferrer" — security risk -->

✅ Correct — cited claim with proper link attributes

<p>According to the
  <a href="https://webaim.org/projects/million/"
     rel="noopener noreferrer">WebAIM Million report</a>,
  over 96% of home pages have detectable WCAG failures.</p>

✅ Correct — sponsored link with correct rel value

<p>We recommend
  <a href="https://partner.example.com/"
     rel="sponsored noopener noreferrer">ToolName</a>
  for its ease of use. (Affiliate link)</p>

Why It Matters

• Trust signals: Google's quality guidelines identify citation of credible sources as evidence of E-E-A-T. Unsupported claims lower trust scores, particularly on informational pages that need the same credibility signals as trust-signals pages.
• User value: Readers can verify claims, explore topics further, and trust content more when sources are cited.
• Link equity: Outbound links to reputable sites do not drain your PageRank. Google treats responsible external linking positively, and MDN's rel reference (opens in new tab) helps clarify when to add nofollow, sponsored, or noopener.

Link Attribute Reference

How to Audit External Links

1. Crawl the site and extract all <a href> tags pointing to external domains.
2. Check each external link for rel="noopener noreferrer".
3. Identify paid/affiliate links missing rel="sponsored".
4. Review long-form content pages with zero external links — add citations where factual claims are made.
5. Periodically re-check external links for 404s (use broken link checkers).

Exceptions

• Necessary utility or compliance pages can be intentionally brief and should not be judged by the same editorial-depth expectations as ranking-focused content.
• AI-assisted drafting is not a failure by itself; flag unsupported claims, missing editorial review, or low-originality output instead.
• When a page has both trust-signal issues and crawl/index problems, make the page eligible to rank first and then improve the content quality signals.

Verification

Automated Checks

• Inspect rendered HTML and HTTP headers to confirm the expected metadata or crawlability signal is present.
• Test the affected URL with Google Search Console or equivalent tooling where relevant.
• Re-crawl a representative page set after deployment.

Manual Checks

• Confirm the change does not create conflicting canonical-url, robots, or structured-data signals.