It seems NoCAPTCHA has almost become a standard in antispam of software. Can we have an extension ?
Should be easy (I think) to add as one of the verification controls.
@emanuele is far more familiar with that class and its set of function s than I am, or specifically how to extend them to add new ones.
I didn't try that hard (i.e. I just wrote the code, not tested at all), but this should work. (Assuming it installs O:-) LOL)