Analyzing the browser environment (canvas fingerprinting, audio stack, battery status) to identify unique devices or spoofed environments.
This is the primary method for automated breaking. captcha+breaker
CAPTCHAs work by presenting challenges that are simple for human brains to solve—such as identifying distorted text or selecting images containing a specific object—but computationally difficult for machines. Over time, these have evolved from simple "type what you see" text boxes to complex behavioral analyses: Analyzing the browser environment (canvas fingerprinting