As I am sure most of you are aware, spam, in the case of unsolicited advertising or off-topic posting as opposed to the processed meat, and bots, the ones that remotely attempt to do stuff on your site, are two of the largest problems for any website that allows comments, signups, creation of content or such like. I have recently been looking into ways to prevent spam and bot-based site registrations in Drupal 7, as on several sites we were experiencing that Captcha’s were simply not preventing enough. Using a various combination of the below modules, we were able to prevent up to 90% of the previous spam and bot-based registration with little effect to regular users.

Drupal Spam Fighting Modules: