Browser-Use Agent Detection

Browser-based agents (Playwright, Selenium, Puppeteer, Browser-Use framework) produce near-identical TLS fingerprints to real browsers, making JA4 alone insufficient. CounterAgent uses JA4H header fingerprinting and behavioural analysis for detection.

Detection Layers

  1. JA4H header ordering — automated browsers often have subtly different header ordering than real Chrome/Firefox
  2. navigator.webdriver — detectable via JavaScript beacon execution
  3. Missing favicon requests — agents skip /favicon.ico despite claiming browser UA
  4. Timing analysis — machine-precise intervals between page loads
  5. Cookie behaviour — agents often don't persist cookies across requests

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