Preventing bot spam without using CAPTCHA.

Here's a solution I use to stop bot spam getting through MarketingMotor lead generation sites.

The form has a couple of hidden fields. Humans don't see them but they get filled in by bots.

<div style="display: none;">
<input type="text" name="phone"><input type="text" name="mobile"></div>

The form processing script checks for those fields. If they're filled out, it's a bot.

if($_POST['phone'] !='' OR $_POST['mobile'] !=''){
 //log it here
 //redirect to the thankyou page without sending the lead to the client
//not a bot so process as usual...

[Update: I've had to make the code that detects spam form submission much more sophisticated since this was published in 2011. I'm not going to publish it because I'd prefer not to let the spammer coders know how we block 250 000 spam form submissions a month.]

© Peter Bowen 2018 | Isle of Wight