“No-CAPTCHA” reCAPTCHA
This stuff kind of seems like an overkill to me.<p>I think asking really simple questions that only a human could understand seems to get the job done most of the time.<p>Perhaps something like: "What is the opposite of bad?" or "How many planet Earths are there?"<p>I've used things like this for a handful of projects and have never had any problems: <a href="https://github.com/kiskolabs/humanizer" rel="nofollow">https://github.com/kiskolabs/humanizer</a>