I have a few web sites with simple forms to collect information from visitors. Sometimes we get spam through the forms, where a computer (or bot) has clearly read the form and filled it out as best as it could. It can be a hassle but for many forms it happens so infrequently that I have ignored it. Well, I have a new site that seems to attract the bots like crazy. So, I had to find a cure, which I thought I’d share.
A Captcha is a barrier that you can put on your site to separate the human users from the computer bots. You have probably seen them – they ask you to re-type squiggly letters that are often hard to read. They can be a pain – but most bots cannot read them. So, they reduce spam from forms by quite a bit.
CAPTCHA stands for “Completely Automated Public Turing test to tell Computers and Humans Apart”.
I found a fantastic web site that will walk you through the process of adding a captcha to an existing form easily – and without any knowledge of php (or really html). How to use captcha: http://www.captcha.biz/index.html. If the whole idea is new to you or you like to read a lot you can start at the beginning. If you’re kind of impatient and moderately knowledgeable (not in php) you can start here: http://www.captcha.biz/captcha-solution.html.
It took me about 15 minutes to go through the site and add the captcha to my form.
After last week’s Byte of PDF converters two Byte readers offered more tool recommendations: