What Is Noopener In SEO

rel=”noopener” is an HTML attribute value that tells the browser to open a link in a new tab without granting the destination page access to the originating page through JavaScript’s window.opener. It is a browser security control, not a search engine ranking signal.

That distinction is where most of the confusion starts. Noopener gets pulled into SEO conversations because it lives inside the same rel attribute that also carries nofollow, a value that does matter for search. The two get lumped together in audits, content guidelines, and link checkers, and the result is a persistent myth: that noopener is something you can optimize.

It is not. Noopener exists to close a specific security hole called tabnabbing, where a malicious page that opens in a new tab reaches back into the original tab and rewrites it. What follows is a walkthrough of what noopener actually does, how it differs from the two attributes it is most often confused with, and when to use it on your own links.

Why Noopener Gets Called an SEO Attribute

The main reason noopener shows up in SEO guides is simple: it shares a home with attributes that do affect search. The HTML rel attribute accepts multiple values, and two of the most discussed in SEO circles are nofollow and sponsored. Both influence how search engines interpret a link. When noopener shows up in the same string, the assumption is that it must do something similar.

It does not. Noopener changes what the browser does with the opened page. It does not change how search engines crawl, index, or weight the link. The confusion gets reinforced by tooling. Most outbound link audit tools report rel="noopener" alongside rel="nofollow" as if they were the same category of finding. Site crawlers flag missing noopener the same way they flag missing nofollow, which trains SEO practitioners to think of them as a matched pair. This is the kind of finding the team at Clickside surfaces in nearly every technical link audit.

That framing is wrong but easy to fall into. Once you see that noopener only governs the browser-level relationship between two tabs, the SEO framing collapses on its own. Treating it as part of link hygiene is fine. Treating it as a ranking lever is not.

How the Noopener Attribute Actually Works

To see why noopener exists, look at what happens when a link opens in a new tab without it. The HTML attribute target="_blank" tells the browser to create a new browsing context, which is just a new tab or window. By default, the browser also creates a connection between that new tab and the original page, exposing the originating page to the opened page through the window.opener JavaScript property. The destination page can read that reference and, in many cases, call methods on it.

Consider a blog post linking to an external tool in a new tab. The reader clicks, the tool opens, and the reader moves their attention to the new tab. If the external page is malicious or compromised, it can use window.opener to redirect the original tab to a fake login page, change its URL, or rewrite its contents. The reader clicks back to what they think is the original article and lands on a phishing page instead. This attack pattern has a name: tabnabbing.

Adding rel="noopener" to the link tells the browser to set window.opener to null on the newly opened page. The connection is severed at the browser level, so the destination cannot reach back into the opener page at all. The behavior is defined in the HTML standard and implemented consistently across modern browsers. The reader still gets a new tab. The destination simply has no handle on the page that sent them. For more on the JavaScript property itself, the MDN documentation for window.opener covers the full interface.

Noopener vs Noreferrer vs Nofollow: Three Different Jobs

Three rel values show up together often enough that they get treated as interchangeable. They are not. Each one has a distinct job, and the fastest way to keep them straight is to remember which system each one talks to.

Noopener is a browser security control. It severs the opener relationship between two tabs to prevent tabnabbing. Noreferrer is a privacy control. It tells the browser to omit the Referer header when the user navigates to the destination, hiding the source URL. In modern browsers, noreferrer also implies noopener behavior, so it doubles as an opener-isolation mechanism when needed. Nofollow is a search engine hint. It tells crawlers that the link should not pass ranking credit in the usual way. It does nothing to the browser’s handling of the tab.

The practical contrast in one line: noopener stops the destination from touching the opener page, noreferrer hides where the click came from, and nofollow tells search engines not to treat the link as an editorial endorsement. Mixing them up is harmless most of the time, but it leads to wrong conclusions, like assuming that adding nofollow to an external link also protects against tabnabbing. Google’s own guidance on qualifying outbound links makes the same separation explicit: nofollow is a crawling and ranking signal, not a browser security mechanism.

When and How to Use Noopener on Your Site

Apply rel="noopener" to any link that uses target="_blank" and points to a destination you do not fully control. Internal links, where the destination is your own site, are low risk because you trust the code, but adding noopener costs nothing and is a reasonable default. For external links where referrer privacy also matters, the combined rel="noreferrer noopener" is the standard safe choice.

Most modern CMS platforms now add noopener automatically when editors open links in a new tab, so verify it in your templates rather than trusting the editor. A quick check of any page that links out to third-party tools, partner sites, or external resources will confirm whether the attribute is present. For a full-site sweep, the Clickside team can run this check programmatically and deliver a clean report.

What to Actually Do With Noopener Going Forward

Treat noopener as part of link hygiene, not as an SEO lever to optimize. The fastest way to put this into practice is a one-time audit of every target="_blank" link on your site.

Confirm each one carries either rel="noopener" or rel="noreferrer noopener". It takes minutes and closes a real security gap.