From a website owner's perspective the Coinhive captcha works exactly like a conventional captcha, such as Google's reCaptcha. The captcha is embeded in an HTML form, runs client side in the user's browser and generates a token. The token is submitted together with the other form data. You can then validate this token on your server through our HTTP API. Demo video showing the proof of work captcha Unlike with a conventional captcha however, the user does not have to “proof they're human”. Instead, the captcha is a “proof of work” – making it uneconomic for spammers to game your system. Free Download: Hidden Content: You must reply before you can see the hidden data contained here.