>So my guess would be they analyze users behaviour on the page where captcha is located, things like mouse movements
If they can track mouse movements why in incognito mode i'm not a human for them anymore? I was expecting same but from what I see it's just a whitelist. And it's OK. Problem is, which you probably didn't care to read, is it's vulnerable to simple clickjacking which opens another weakness - i can use your click on my page to get your reCAPTCHA token and feed it to my spam bot.
I'm actually happy with No CAPTCHA, because it's making progress. But it's not good enough (see the rest of comments, it could be a background AJAX request instead).
If they can track mouse movements why in incognito mode i'm not a human for them anymore? I was expecting same but from what I see it's just a whitelist. And it's OK. Problem is, which you probably didn't care to read, is it's vulnerable to simple clickjacking which opens another weakness - i can use your click on my page to get your reCAPTCHA token and feed it to my spam bot.
I'm actually happy with No CAPTCHA, because it's making progress. But it's not good enough (see the rest of comments, it could be a background AJAX request instead).