Understanding Referrer Loss and Direct Traffic in Sealmetrics

Sealmetrics is a privacy-first analytics platform that does not use cookies. This means it relies heavily on the referrer to determine the origin of traffic. However, in many modern websites, the referrer is often lost due to technical reasons — which can lead to a significant portion of traffic being misclassified as Direct.

This document outlines all the technical reasons why the referrer might be lost, and explains why Direct traffic may appear unusually high in some websites.

Without cookies, Sealmetrics cannot track individual users or sessions across time. Instead, it determines the source of a visit by analyzing the referrer header of each hit:

Losing the referrer means that Sealmetrics cannot correctly attribute the source of the visit — and by default, such hits are classified as Direct traffic.

Server-side redirects often strip the original referrer, especially when crossing domains.

When navigating between different domains, modern browsers strip the referrer unless a proper referrer-policy is set.

If the website explicitly sets Referrer-Policy to values like no-referrer or strict-origin, the browser will remove the referrer entirely.

When a user moves from a secure page (HTTPS) to a non-secure one (HTTP), the browser blocks the referrer for security reasons.

Clicks from apps like Facebook, Gmail, or LinkedIn often lack a traditional browser referrer.

Some browsers restrict or block the referrer when browsing privately.

Tools like Bit.ly, Outbrain, or custom redirectors may cause referrer loss due to intermediate redirects.

Redirections via window.location, location.replace, or window.open may cause the browser to discard the original referrer.

Many email clients and messaging apps strip the referrer when a link is clicked.

Privacy-focused browsers or extensions like Brave, uBlock Origin, or DuckDuckGo may block referrers by default.

If a page is loaded inside an iframe or embedded webview, referrer behavior can be inconsistent or blocked.

Improper use of <base> or canonical tags can confuse browsers and lead to referrer anomalies.

Using JavaScript to open pages (e.g., element.click(), window.location) can suppress the referrer depending on how it’s implemented.

If a link is triggered automatically (e.g., via setTimeout or onLoad), browsers may treat it as a forced redirect and remove the referrer.

Meta tag redirects (<meta http-equiv="refresh">) can also strip the referrer in some cases.

Cross-origin requests that don’t explicitly allow referrer headers will result in blocked referrer data.

If a CSP header sets referrer no-referrer, the browser is instructed not to send referrer information.

In specific configurations, using target="_blank" without proper rel attributes can alter or suppress referrer behavior.

If your website performs frequent redirects, uses link shorteners, relies heavily on JavaScript navigation, or lacks proper referrer-policy headers, Sealmetrics may receive hits without referrer data. When this happens, those hits are marked as Direct traffic.

This means your Direct traffic numbers may appear abnormally high, but that doesn’t necessarily indicate that users are typing your URL into the browser. In many cases, these are visits from SEO, social, or campaign sources where the referrer has been lost due to technical implementation details.

Keeping referrer integrity intact ensures that your analytics data stays meaningful — even without cookies.