Strengthening Web Privacy with the Referrer-Policy HTTP Header

Understanding the Referrer-Policy Header

The Referrer-Policy HTTP header is a security feature that helps web developers control how much information the browser includes in the “Referer” header when navigating from one page to another. The Referer header contains the URL of the page that initiated the request, providing information about the user’s browsing history.

How the Referrer-Policy Header Works

The Referrer-Policy header offers several directives, each controlling the behavior of the Referer header in different ways:

  1. no-referrer: This directive specifies that no referrer information should be sent in the HTTP request header when navigating from one page to another. This is the most restrictive option.
  2. no-referrer-when-downgrade: In this case, the referrer information is sent only when navigating to a less secure destination (from HTTPS to HTTP). When navigating from HTTPS to HTTPS, or from HTTP to HTTP, no referrer information is included.
  3. origin: This directive sends the origin (i.e., the protocol, host, and port) of the referring page, but no path information. For example, if you’re on a page at, the Referer header would contain
  4. origin-when-cross-origin: Similar to “origin,” but it includes the full URL when navigating within the same origin. When navigating to a different origin, it sends only the origin information.
  5. same-origin: With this directive, the Referer header is sent only when navigating to a page within the same origin. It doesn’t include referrer information when crossing origins.
  6. strict-origin: This directive is similar to “origin,” but it doesn’t send referrer information when navigating from HTTPS to HTTP.
  7. strict-origin-when-cross-origin: This is a combination of “strict-origin” and “origin-when-cross-origin.” It sends the full URL when navigating within the same origin and only the origin when navigating to a different origin.
  8. unsafe-url: This is the default behavior if no Referrer-Policy header is specified. It sends the full URL as the referrer information.

Why the Referrer-Policy Header Is Essential

  1. Privacy Protection: The Referrer-Policy header helps protect user privacy by limiting the amount of information shared about their browsing habits. This is especially important when navigating from secure (HTTPS) to non-secure (HTTP) sites.
  2. Mitigating Information Leakage: By controlling the referrer information, the header reduces the risk of sensitive data leakage through URL parameters or query strings.
  3. Cross-Origin Security: The ability to specify different policies for same-origin and cross-origin requests enables fine-grained control over information sharing with external websites.
  4. Compliance with Privacy Regulations: Implementing strong privacy controls, like those offered by the Referrer-Policy header, helps websites comply with privacy regulations such as GDPR (General Data Protection Regulation) and CCPA (California Consumer Privacy Act).

Implementing the Referrer-Policy Header

Implementing the Referrer-Policy header is relatively straightforward. You can configure your web server to include the header in your HTTP responses. The specific implementation may vary depending on your web server software.


The Referrer-Policy HTTP header is a powerful tool for enhancing user privacy and security on the web. By controlling the information shared in the Referer header, web developers can mitigate privacy risks, protect sensitive data, and comply with data protection regulations. As part of a comprehensive web security strategy, implementing the Referrer-Policy header is a step toward a more secure and privacy-conscious online experience for your users.

Jacob Billings
PhD Candidate - Complex Systems

I am a software engineer, linguist, and researcher of Complex Systems. I hold a bachelor's degree in Middle Eastern Studies from the University of Utah, a Master’s degree in linguistics from Francisco Marroquín University in Guatemala City, and I am a doctoral candidate in Complex Systems at the Polytechnic University in Madrid, Spain.

Software Development: I bring over 20 years of experience in developing software for multiple clients in various environments. I have a solid knowledge of PHP, Javascript, MySQL, NoSQL, Python, and Java.

Over my career, I have had the opportunity to work on projects for some of the most recognized brands on the planet. Brands like Marriott Hotels, Microsoft, Ashland Chemical, Capital One Credit Cards, Cadbury Schweppes, GE and more. This has given me an in-depth understanding of my client's challenges as they grow. I know how to get a company from startup to maturity with technology. My specialties are in E-commerce(specifically Magento), process automation, and security.