Honeypots take care of most basic bots. If you need captcha, you can use Math Question like in http://random.irb.hr/signup.php http://random.irb.hr/signup.php Y

Honeypots take care of most basic bots. If you need captcha, you can use Math Question like in http://random.irb.hr/signup.php http://random.irb.hr/signup.php You can also add extra security with time elapsed between loading the page and form submission, if it's less than 5 seconds it's most likely a bot.