Negative Captcha Alternatives

Negative Captcha is described as 'A negative captcha has the exact same purpose as your run-of-the-mill image captcha: To keep bots from submitting forms. Image ("positive") captchas do this by implementing a step which only humans can do, but bots cannot: read jumbled characters from an image' and is a Anti-Spam tool. There are more than 10 alternatives to Negative Captcha for a variety of platforms, including Web-based, Self-Hosted, SaaS, PHP and Wordpress apps. The best Negative Captcha alternative is reCAPTCHA, which is free. Other great apps like Negative Captcha are Procaptcha, hCaptcha, mosparo and UniqPin.