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How to Add Nofollow to External Links in WordPress

Last updated on August 12, 2026

Key Takeaways

• Single toggle, no nested options

• Processes `the_content` filter (covers posts, pages, and custom post types)

• Adds `rel=”nofollow”` and `target=”_blank”` to links pointing to external domains

• Does not modify internal links (links to your own domain)

• Does not modify existing link attributes (preserves user-set values)

What Is the Add Nofollow feature?

WordPress’s default behavior is to render links as written: <a href="https://example.com">text</a>. Add Nofollow intercepts this at the the_content filter and adds two attributes to all external links:

  • rel="nofollow": Tells search engines not to pass link equity to the linked page
  • target="_blank": Opens the link in a new browser tab (keeps the visitor on your site)

Internal links (links pointing to your own domain) are not modified. The feature does not change the link’s text, URL, or any other attributes you’ve manually set.

Why You Need It

  • SEO: rel="nofollow" tells search engines like Google not to pass PageRank to the linked site. This concentrates your link equity on your own content rather than spreading it to external sites
  • User experience: target="_blank" opens external links in a new tab, so visitors don’t navigate away from your site. They can read the external content and still have your site open
  • Spam reduction: Spammers and low-quality linkers avoid sites that nofollow external links, because the backlink they get from your site has no SEO value
  • Compliance: Some sites are required by policy or regulation to nofollow certain external links (e.g., sponsored content per Google guidelines)

The trade-off is that some legitimate sites may not link to you if you nofollow all externals (they want the link equity back). For most sites, the SEO and UX benefits outweigh this concern.

How to Use Add Nofollow in Classic Monks

Step 1: Navigate to Settings

Click into the Classic Monks plugin settings in your WordPress dashboard.

Step 2: Go to the Content Subtab

Click on the Core menu, then click the Content subtab.

Step 3: Enable Add Nofollow to External Links

Scroll to the SEO and Visibility section and toggle on Add nofollow to External Links and Open in New Tab.

SEO settings for external links

Step 4: Save Changes

Click Save Changes.

Step 5: Verify

Open any post with external links on the front-end. View the page source. External links should have rel="nofollow" target="_blank" in their <a> tags. Internal links (to your own domain) should be unchanged.

Link settings modal dialog External link to classicmonks.com

Configuration Options

Option Description Default
Add nofollow to External Links and Open in New Tab Master toggle. Applies both attributes. Off

No nested options. The toggle is global.

What Gets Modified

Link type Before After
External link in post content (<a href="https://other-site.com">text</a>) No rel, no target <a rel="nofollow" target="_blank" href="https://other-site.com">text</a>
Internal link in post content (<a href="/about/">text</a>) Unchanged Unchanged
External link in custom HTML blocks No rel, no target Modified (if processed by the_content filter)
Links in widgets Depends on widget Modified (if widget calls the_content filter)
Links in navigation menus Unchanged Unchanged (menus don’t go through the_content)
Links in comments Unchanged Unchanged (comments are filtered separately)

How the Feature Decides “External”

The feature compares each link’s host to your site’s host (home_url()‘s host). If they match (including www vs non-www and subdomain handling), the link is internal. If they don’t match, the link is external and gets the attributes added.

Edge cases:

  • Subdomain links: A link to blog.yoursite.com is considered internal if your site is at yoursite.com AND the subdomain is configured. Otherwise, it’s external.
  • Protocol-relative links: A link starting with // (e.g., //cdn.example.com) is treated as external by default.
  • Anchor-only links: A link starting with # is not modified (it’s a page anchor, not an external link).
  • Mailto and tel links: A mailto: or tel: link is not modified (it’s not an external HTTP link).
  • Same-site cross-domain: A link to yoursite.com from www.yoursite.com is considered internal if both resolve to the same site.

Developer Notes

This feature is a single toggle with no developer hooks currently exposed. The feature-specific logic is loaded conditionally when the toggle is enabled.

Options used:

Option Type Default
Feature toggle Boolean false

Troubleshooting

Cause: The toggle is off, or a caching plugin is serving a cached version of the page.
Fix: Verify the toggle is on. Clear all caching layers. View the page source to confirm the attribute is in the rendered HTML.

Cause: The site host comparison is failing. This happens when the site URL and the home URL are different (e.g., WordPress is configured with www.yoursite.com but the database stores yoursite.com).
Fix: Check Settings > General > WordPress Address and Site Address. They should match. If they don’t, update them to match, or use the cm_nofollow_external_link_domains filter to manually define what’s external.

Cause: The feature’s default behavior is to preserve existing attributes, but a custom filter may be overwriting them.
Fix: Check for custom code that filters the_content and modifies link attributes. The default behavior preserves rel="dofollow" and other existing rel values, so this is unusual.

Cause: The feature adds nofollow, but Google requires sponsored for paid placements.
Fix: Use the cm_nofollow_link_attributes filter to add “sponsored”: add_filter( 'cm_nofollow_link_attributes', function( $attrs ) { $attrs[] = 'sponsored'; return $attrs; } );. This adds both nofollow and sponsored, which is the safest signal for paid content.

Cause: The the_content filter only runs on singular post views. Archive pages (categories, tags, search results) use the_excerpt or direct template calls.
Fix: If you need nofollow on archive pages, extend the filter: add_filter( 'the_excerpt', function( $excerpt ) { return apply_filters( 'the_content', $excerpt ); } );. This is a workaround, not a fix; the canonical solution is to use a theme that calls the_content on archive pages.

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