Bielser Engineering

Understanding Referrer Policy: Controlling Referrer Information

2025-01-15
5 min read

The Referrer Policy is an HTTP header and HTML attribute that determines how much referrer information is sent with requests originating from your website. It provides a way to balance user privacy with functionality, making it a crucial tool for modern web development.

1. What is Referrer Information?

Referrer information is part of an HTTP request, indicating the URL of the webpage that referred the user to the current page. For example, if a user clicks a link on your website, the destination site may receive the full URL of your page as the "Referrer."

While this can be useful for analytics and functionality, it may also expose sensitive information, such as query parameters containing user data.

2. How Referrer Policy Works

The Referrer Policy header or attribute lets you control how much information is shared with the destination. The policy can be set globally via HTTP headers or on individual elements using HTML attributes.

Here are some common directives:

  • no-referrer: No referrer information is sent.
  • no-referrer-when-downgrade: Sends referrer information only over secure HTTPS connections, not HTTP.
  • origin: Sends only the origin (e.g.,https://example.com), omitting the path and query.
  • strict-origin-when-cross-origin: Sends the origin for cross-origin requests and the full referrer for same-origin requests.

Example HTTP header:

Referrer-Policy: no-referrer-when-downgrade

3. Why Referrer Policy is Important

  • Protects User Privacy: Reduces the risk of exposing sensitive information via referrer URLs.
  • Enhances Security: Prevents data leaks when navigating between secure (HTTPS) and insecure (HTTP) environments.
  • Improves Compliance: Meets data protection standards like GDPR by limiting shared user information.

4. Use Cases

Referrer Policy is beneficial for:

  • E-commerce Sites: Prevent sensitive transaction details from being exposed in URLs.
  • Content Platforms: Control how referrer information is shared with third-party advertisers or analytics providers.
  • Secure Applications: Protect sensitive user data in query strings or path parameters.

5. Implementation Best Practices

  • Set a global Referrer Policy via HTTP headers for consistent behavior across your site.
  • Use strict-origin-when-cross-origin for a balance of privacy and functionality.
  • Customize policies for specific links or embedded elements using the HTML referrerpolicy attribute.

6. Bielser Engineering’s Expertise

At Bielser Engineering, we help you implement Referrer Policy effectively by:

  • Analyzing your website’s needs to recommend optimal policies.
  • Configuring HTTP headers and HTML attributes for consistent and secure behavior.
  • Testing and monitoring to ensure the policy aligns with your goals and user expectations.

7. Take the Next Step

Interested in enhancing user privacy and security with Referrer Policy? Contact Bielser Engineering today to get started.

Final Thoughts

Referrer Policy is a powerful tool for controlling how your website shares referrer information, improving privacy and security for your users. At Bielser Engineering, we provide the expertise you need to implement these policies effectively, ensuring a safer web experience for all.

Ready to enhance your website’s privacy? Contact us today and take the next step toward a more secure web presence.