title: using captcha in mobile apps
body: <p>I am looking for an alternative for captcha to use in our mobile applications. We are writing a mobile application in iOS and Android. The web application is already exist. In the web page we are using captcha to ensure only genuine customers are applying and to prevent denial of service type attacks. </p>
  
  <p>So from mobile app also we need to take care of these. Any body came across the same situation? Is it recommended to use captcha in native mobile apps?</p>