I replaced CAPTCHA with passive biometrics after AI hit 91% bypass rate — 7 biological signals, no puzzles, free tier

Source: Dev.to

CAPTCHA is broken

AI now bypasses reCAPTCHA at 91%+ success rates. Every CAPTCHA you add costs you 17‑29% conversion. It is a bad trade that gets worse every year.

What I built

ANIMA collects 7 passive biological signals during normal page interaction — no puzzle, no challenge, no user friction:

• Neuromotor tremor (8‑12 Hz motor neuron oscillation)
• Inter‑tap interval variance (stochastic neural timing)
• Associative response latency (cognitive processing time)
• Pointer dynamics (Fitts’ Law biomechanics)
• Scroll behavior entropy (Shannon entropy of scroll patterns)
• Device motion (accelerometer signatures)
• Cross‑signal correlation

These are physical properties of biological nervous systems. AI cannot fake a tremor without simulating motor neurons.

How it works

One script tag. Verification runs in 0.4 seconds invisibly. Returns a signed JWT with a confidence score. You verify the token server‑side before processing any form submission.