Show HN: A CAPTCHA based on 3D spatial recognition(spatial-captcha-frontend.vercel.app)

spatial-captcha-frontend.vercel.app

Show HN: A CAPTCHA based on 3D spatial recognition

https://spatial-captcha-frontend.vercel.app

I got tired of clicking traffic lights and fire hydrants, so I built a CAPTCHA that asks you to rotate a 3D object to match a target angle.

Try it here: https://spatial-captcha-frontend.vercel.app

The idea is simple — humans are naturally good at understanding 3D space, but bots aren't. A bot would need to figure out the spatial orientation of a 3D model rendered in a WebGL viewport, which is a much harder problem than solving text or image classification CAPTCHAs.

Under the hood it uses Three.js for rendering, quaternion comparison on the backend for angle matching (45° tolerance), and the whole thing drops into any site with two lines of HTML. Verification flow is the same as reCAPTCHA — pass token issued on success, server-side /siteverify endpoint.

Curious what you all think — is 3D spatial reasoning actually a durable defense, or will multimodal models eat this for breakfast in a year?

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