Impossible travel: What it is, how it works, and how to defend against it

Impossible travel detection leverages a fundamental physical constraint—that a person cannot be in two places at once—to identify and mitigate potential security threats like credential theft and account takeover. By comparing login data points such as location and timestamp, the detection system flags suspicious activity if the implied travel speed between locations exceeds feasible limits, typically benchmarked against commercial aviation speeds. Despite its simplicity, naive implementations can generate many false positives due to factors like VPN usage, mobile network routing, and GeoIP inaccuracies. To enhance accuracy, mature systems incorporate device fingerprinting, IP reputation, user behavior baselines, and session context to filter out benign anomalies. WorkOS Radar offers a sophisticated implementation of impossible travel detection by integrating with AuthKit and using device fingerprinting and geolocation tracking to minimize false positives while allowing configurable response actions. This detection mechanism, part of a broader security framework, provides a high-signal tool for identity security by exploiting the immutable laws of physics to thwart attackers, offering seamless integration and real-time insights for users seeking robust authentication threat protection.