Codetcha

I've sat on the concept for a long time and it has had many names but I've got a bit of free time now so I decided to create a proof of concept. It isn't perfect yet and there may be false positives due to a few bugs but if you read my blog you know I like to release code early :)

So what is it I hear you ask? Well Codetcha is CAPTCHA but not in the traditional sense, it purposely creates code bugs and uses the developers debugging skills to determine if he/she is human or not. In the first version I've used Javascript as the error prone code and a PHP mirror behind the scenes to get the relevant value. However any programming language could be used, I decided on Javascript because you can use the native debugging in the browser to help you pass the test.

It's worth noting that this sort of system couldn't be used on a non-technical forum or blog because it assumes knowledge of a programming language but it could be used on technical blogs and forums.

Update...

Fixed more bugs, reduced the settings slightly. I'll release the source code soon once I've refined it a bit more.

Update again...

I've fixed many bugs, reduced the code by 50% and improved the replace algorithm.

Codetcha demo