I have just finished developement of a captcha mod for traffic exchanges. This mod is an anti-cheat feature which will ask the user to input a 6 digit code every so many pages surfed. In the case of the LJ Script it will replace the surf verification feature that is default in that script, but may be turned off in the admin area (which will return your site to using the questions as before).

Captcha is a common turing test feature among many of the latest open-source scripts and e-commerce websites and is very efficient at preventing bots from using a particular service. If you’re worried about bot activity and would like to purchase this mod now please visit my Mods page. It costs $45 and can be running in as little as 15 minutes.

Demo: Captcha Mod Demonstration
Demo: Sign up and surf to see it in action

The GD library allows a server to render simple graphics. It’s not photoshop, but it is highly useful. Especially for CAPTCHA pages, a typical feature which I am in the middle of developing for traffic exchanges.

CAPTCHA stands for ‘Completely Automated Public Turing test to tell Computers and Humans Apart‘, and typically uses the GD library to create a graphic with a random string or word, sometimes distorted, that a human can decipher and input back to the server but bots can not.

There are many other uses for the GD library, but this is an extremely common one these days.

When developing a script which uses image rendering through the GD library sometimes (usually) you get to a point where you have to check if the library is installed on the server. It’s a big plus to a developer if the code he’s writing can actually work.

So I was really pleased when I found a simple script by Dagon Design that tells you straight out that GD is installed. You can look at phpinfo() to find this info, but I find this nicer and more to the point.

Perhaps this will be as useful to you as it will be to me:
Script: Checking for GD support on your server