Recent Research and Trends on Private Browsing/Incognito Mode: Challenges and Limitations

Private browsing—often called incognito mode—has long been marketed as a digital cloak, a way for users to surf the web without leaving a trace. But in recent years, this promise has come under increasing scrutiny. As headlines and lawsuits mount, a growing body of research reveals a stark disconnect between what users expect from private browsing and what it actually delivers.

In April 2024, a SecurityWeek article made waves by highlighting that incognito mode fails to prevent websites from tracking users via IP addresses or to stop internet service providers from logging activity. Around the same time, Google found itself at the center of a legal firestorm. The company agreed to delete billions of data records collected from users in incognito mode, a move that Wired described as the moment the "incognito mode myth" fully unraveled. Despite this high-profile settlement, litigation continues, as detailed in ongoing legal coverage, with individual damages claims still emerging. The NPR report on Google's agreement to destroy millions of user search histories underscored just how much data was being collected in supposedly "private" sessions.

Yet the legal drama is only part of the story. Technically, private browsing's limitations are just as significant. For example, Google Analytics can still track users in incognito mode, even if it can't always link sessions together. Kaspersky points out that incognito mode only hides activity from others using the same device, not from ISPs, employers, or tracking software. Even browser explanations are often generic and easily misinterpreted, as Pedro Monjo notes, leaving users with a false sense of security. And while incognito mode prevents browsers from saving history and cookies, Kinsta reminds us that websites, servers, and search engines can still track user activities.

Perhaps most concerning is the gap between user perception and reality. A University of Chicago study found that users significantly overestimate the protections provided by private browsing, even after reading browser-provided information. Browser fingerprinting techniques can still identify and track users, creating unique digital fingerprints that persist across sites. In some cases, incognito mode can even be less safe: Reddit discussions highlight that most browsers don't allow security extensions to run in private mode unless explicitly enabled.

Academic research backs up these concerns. A 2018 USENIX study found that users overestimate private browsing's ability to protect against online tracking and targeted advertising, using it mainly to hide local history. Stanford researchers have identified technical vulnerabilities, such as DNS caching and OS-level memory swapping, that can leak browsing activity. Misconceptions are widespread: a 2019 study of 460 participants found most users incorrectly believe incognito mode prevents companies like Google from recording search history. And in a world where privacy is increasingly politicized, CNN has reported on the serious privacy concerns that arise when private browsing fails to prevent third-party tracking or law enforcement access to browsing data.

The evidence is clear: there is a significant gap between what users expect from private browsing and what it actually provides. Legal actions against Google have brought these issues into the spotlight, but the technical and human factors remain. As the industry grapples with how to provide transparent, effective privacy tools, users must remain vigilant—and perhaps a bit skeptical—about what incognito mode can really do.