title: How to block Alexa and Similar Web to access website
body: <p>I need to perevent Alexa and Similar web from accessing my website completely.
  I understand that it's can be done with robots.txt, but as far as i know it's not enough and they are collection data with simple extensions or something similar.</p>
  
  <p>Any ideas or solutions?</p>
  
  <p>Thank you in advance.</p>