Understanding rel=”noopener noreferrer” in HTML: Why It Matters for Security and Privacy

When creating links (<a> tags) in HTML, developers often use the target="_blank" attribute to open a link in a new browser tab. However, using target="_blank" without proper precautions can create serious security vulnerabilities and expose users’ private information.
To address these concerns, modern best practices recommend adding rel="noopener noreferrer" to external links.

In this article, we’ll dive deep into what rel="noopener noreferrer" means, why it’s important, how it protects your website, and how to use it correctly.

What Is target="_blank"?

First, let’s understand the background.
When you add target="_blank" to an <a> tag, the browser opens the link in a new tab or new window.

Example:

<a href="https://example.com" target="_blank">Visit Example</a>

This is a very common practice because:

• It keeps the user’s current page open.
• It improves user experience when linking to external sites.

However, it introduces a hidden security risk.

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The Security Problem with target="_blank"

When a link is opened with target="_blank", the newly opened page can gain limited access to the original page through the window.opener object in JavaScript.
This access allows the new page to perform potentially dangerous actions, such as:

• Redirecting the original page to a phishing site.
• Manipulating content on the original page.
• Stealing user data or cookies.
• Spoofing trust by pretending the original page is still safe.

This type of attack is called reverse tabnabbing — and it is a very real threat.

Introducing rel="noopener noreferrer"

To solve this problem, HTML5 introduced two important keywords for the rel attribute:

• noopener
• noreferrer

You can use them individually or together for maximum protection.

What Does noopener Do?

rel="noopener" instructs the browser not to allow the newly opened page to access the window.opener object.
In simpler terms:

• The new page cannot control or change the original page.
• It prevents reverse tabnabbing attacks.

Example:

<a href="https://example.com" target="_blank" rel="noopener">Visit Example Safely</a>

✅ Now, example.com cannot do anything malicious to the page the user came from.

What Does noreferrer Do?

rel="noreferrer" provides an extra layer of privacy.

It prevents the browser from sending referrer information to the new page.
Normally, when a user clicks a link, the destination site receives the URL of the page where the user clicked from — this is called the HTTP referrer.

Using noreferrer:

• The destination site won’t know where the visitor came from.
• It protects user privacy and reduces tracking.

Example:

<a href="https://example.com" target="_blank" rel="noreferrer">Visit Example Privately</a>

Why Use Both: rel="noopener noreferrer"

In practice, developers often combine both for full safety:

<a href="https://example.com" target="_blank" rel="noopener noreferrer">Visit Example Securely</a>

Benefits of combining them:

Real-World Example of an Attack (Reverse Tabnabbing)

Imagine you have a blog and you link to an unknown external article with target="_blank" but no rel="noopener noreferrer".
If the external article’s website is malicious, it could execute JavaScript like this:

window.opener.location = 'https://phishing-site.com';

This code redirects your blog page (the opener) to a phishing site — even though the user thinks they’re still on your trusted blog!

This attack could:

• Steal login credentials.
• Trick users into downloading malware.
• Damage your website’s reputation.

Thus, always use rel="noopener noreferrer" to defend against this!

Should You Always Use rel="noopener noreferrer"?

Yes, especially when:

• You are linking to external websites.
• You are using target="_blank" to open a new tab.
• You want to protect your users’ security and privacy.

If you are linking to internal pages of your own website, it’s generally not necessary — but using it still doesn’t hurt.

Best Practices for Using rel="noopener noreferrer"

Here are a few practical tips:

• Always add rel="noopener noreferrer" when using target="_blank".
• For better SEO, you can also add rel="nofollow" if you don’t want search engines to pass authority to external links.
• Make sure your CMS (like WordPress) or website builder inserts rel="noopener noreferrer" automatically — or manually edit the link HTML.

Example with all common link attributes:

<a href="https://example.com" target="_blank" rel="noopener noreferrer nofollow">External Resource</a>

Conclusion

Adding rel="noopener noreferrer" to your external links is a small step that brings huge security and privacy benefits.
It helps protect your website and users from malicious activities like reverse tabnabbing and prevents sensitive data from leaking through referrer headers.

In today’s internet environment where user trust and website security are more important than ever, following these simple practices shows your professionalism and care for your visitors.

Whenever you create links that open in a new tab — always remember:
👉 target="_blank" + rel="noopener noreferrer" = Safe and secure linking!