This widget implements CoinHive proof-of-work captcha for your Yii2 web application. From a website owner’s perspective the CoinHive captcha works exactly like a conventional captcha, such as Google’s reCaptcha.

The captcha is embeded as a usual Yii2 widget for ActiveForm with any of your model. User client side generates a token. The token is submitted together with the other form data. Then bundled captcha validator confirms this token on your server through CoinHive HTTP API.

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.

Links

https://coinhive.com/documentation/captcha — CoinHive captcha documentation;
http://www.yiiframework.com — Yii framework;
https://maximals.ru — widget author’s website (Russian).