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What Are External Links and Why Do They Matter for SEO?

External links (also called outbound links) are hyperlinks on your webpage that point to a different domain. For example, if your blog post cites a study on another website, that is an external link. An external link checker like this tool fetches your page and performs a full outbound link check on every one of those links.

External links matter for SEO for two distinct reasons. First, linking out to high-quality, relevant sources is a positive quality signal. Google's Quality Rater Guidelines describe authoritative external citations as a marker of expertise and trustworthiness (E-E-A-T). Pages that link to credible sources are perceived as more informative and reliable than pages that never link out.

Second, broken or low-quality outbound links are a negative quality signal. A page filled with broken external links signals to Google that the content is poorly maintained and out-of-date. Google's John Mueller confirmed in a 2021 Webmaster Hangout that broken links are a quality signal that Google considers when evaluating pages. Regular outbound link checks using our free external link checker prevent this from happening.

External links vs. backlinks

It is important to distinguish between external links and backlinks. External links (outbound links) are links leaving your site, meaning your site linking to others. Backlinks (inbound links) are links coming to your site, meaning other sites linking to you. Our external link checker audits your outbound links. For checking links coming into your site, use our Toxic Link Checklist.

Broken Outbound Links: How to Find and Fix Them

A broken outbound link is an external link that returns an error when visited, typically a 404 (Not Found), 410 (Gone), 403 (Forbidden), or 5xx (Server Error). These happen naturally over time as external websites restructure their content, change URLs, or shut down entirely. Without a regular outbound link check, broken links accumulate silently.

Why broken outbound links hurt SEO

Broken outbound links affect your site in three ways. First, they harm user experience. When a user clicks an external link and lands on a 404 page, they lose trust in your content. Second, they are a page quality signal. Google evaluates how well a page maintains its outbound links as part of its quality assessment. Third, they waste the intent of the link. If you cited a source to support a claim and that source is now broken, the citation no longer supports anything.

How to fix broken outbound links

When our external link checker finds a broken outbound link, you have three options: (1) Find the new URL of the resource and update the link. Use the Wayback Machine (web.archive.org) to find archived versions of disappeared pages. (2) Link to an equivalent resource on a different authoritative site. (3) Remove the link entirely if no good replacement exists. Do not leave broken outbound links pointing to error pages. They provide no value and signal poor page quality.

Run an outbound link check at least once per quarter on your most important pages. High-traffic landing pages, cornerstone content, and pages with many external citations are the highest priority.

Nofollow, Sponsored & UGC: Which Rel Attribute to Use on Outbound Links?

Google recognizes four link relationship attributes that affect how external links are treated: dofollow (default, no attribute needed), nofollow, sponsored, and ugc. Using the wrong attribute, or missing a required one, can violate Google's link spam policies.

Dofollow outbound links (default)

By default, all links are dofollow, meaning they pass PageRank from your page to the destination. Natural editorial outbound links to authoritative sources (studies, news articles, tools, official documentation) should be dofollow. This is how the web was designed to work, with links as endorsements, and it benefits both your page quality score and the destination site.

Nofollow outbound links (rel="nofollow")

rel="nofollow" tells Google not to follow or pass PageRank to the linked page. Use nofollow on links you do not want to endorse: links in comment sections before moderation, links to login pages, links to pages you are legally required to link to but do not editorially vouch for, and links to low-quality or untrusted external sources.

Sponsored outbound links (rel="sponsored")

rel="sponsored" is required on all paid external links, affiliate links, sponsored content, paid advertisements, and any link you received compensation for (money, products, or services). Failing to mark paid outbound links as sponsored is a violation of Google's link spam policies and can result in a manual penalty.

UGC outbound links (rel="ugc")

rel="ugc" marks links in user-generated content, comments, forum posts, and community contributions. This attribute signals that the link was placed by a user, not the site editor, and that you may not have reviewed or endorsed its quality.

Our outbound link checker identifies all nofollow, sponsored, and ugc-tagged external links on your page so you can audit whether each one is correctly classified.

Anchor Text for External Links: Best Practices

The anchor text of an external link, meaning the visible clickable text of the hyperlink, serves two purposes. First, it tells users what they will find at the destination. Second, it passes topical context signals to Google about both your page and the destination page.

Descriptive anchor text vs. generic or empty anchors

Outbound links with descriptive anchor text (according to this Stanford study on sleep deprivation) are more valuable than links with generic anchors (click here, read more, source) or no anchor text at all. Our external link checker specifically flags external links that have no visible anchor text, typically image links without alt text or JavaScript-generated links, as these contribute nothing to your page's topical relevance signals.

Anchor text and E-E-A-T

From a Google Quality Rater perspective, pages that link to external sources with specific, informative anchor text demonstrate greater editorial care and expertise. This supports your E-E-A-T (Experience, Expertise, Authoritativeness, Trustworthiness) signals, a growing factor in how Google evaluates content quality. Pair your outbound link audit with a Title and Meta Checker to ensure full on-page quality.

External Links, target="_blank", and the noopener Security Issue

A widely used practice is to open external links in a new browser tab using target="_blank". This keeps users on your page while they browse the linked resource. However, without a specific security attribute, this practice creates a reverse tabnapping vulnerability.

What is reverse tabnapping?

When a user clicks a target="_blank" link that lacks rel="noopener", the destination page gains access to the window.opener object of your original page. A malicious destination site could use this to silently redirect your page to a phishing site in the background, and when the user switches back to your tab, they land on a fake login page.

The fix: always add rel="noopener noreferrer"

Every external link with target="_blank" should include rel="noopener noreferrer". The noopener attribute removes access to window.opener, eliminating the tabnapping vulnerability. The noreferrer attribute additionally prevents the referrer header from being sent to the destination, protecting your users' privacy. Our outbound link check scans every target="_blank" external link and flags any that are missing these attributes.

Modern browsers (Chrome 88+, Firefox 79+) now default to noopener behavior on target="_blank" links, but explicitly adding the attribute is still best practice for cross-browser compatibility and clarity.

How Many Outbound Links Should a Page Have?

There is no universal rule for how many external links a page should have. The right number depends on content type, length, and purpose. However, several guidelines and best practices help answer the question of how to find outbound links on a site and decide whether you have too many or too few.

Quality over quantity for outbound links

Every outbound link you add is effectively a vote of confidence in the destination page. Linking to authoritative, relevant sources strengthens your page's E-E-A-T. Linking to random, low-quality, or irrelevant external sites does the opposite. Our external link checker flags suspicious TLDs and identifies HTTP-only external links as indicators of potential link quality problems.

The PageRank dilution concern

Every page has a finite amount of PageRank to distribute. Each outbound dofollow link passes a fraction of that PageRank to the destination site. Pages with very high numbers of outbound links may dilute their own internal PageRank flow. This is a real but often overstated concern. For most content pages with a natural number of citations (5–20 external links), this is not a significant issue. Pages that function as link directories with hundreds of outbound links are a different matter and should use nofollow appropriately.

Use our Internal Link Counter alongside this outbound link check to get a complete picture of both your internal and external link profile.