CAPTCHA and ColdFusion

While getting caught up on lists, I came across an interesting thread on CAPTCHAs, or programs that attempt to tell humans apart from computers. We most often come across such technology when registering or leaving a comments on weblogs and we are asked to type in a sequence of numbers and/or letters from a distorted image. Of course, this is to prevent spammers from leaving such constructive comments as “Great site! Visit!”.

Someone pointed out a ColdFusion implementation at called cfx_captcha. I haven’t tried it, but it looks like it would do the trick. Is anyone else out there using something like this to protect their forms? If so, what are you using, and where can the ColdFusion community find it? (And please — no comments about “enlargements”.)

9 Responses to CAPTCHA and ColdFusion

  1. Matt Liotta says:

    OpenXCF ( has a CFX tag named ImageString that allows one to create an image based on the contents of a string. It does this by taking an existing image and adding the string on top of it. This is perfect for CAPTCHA since it allows you to use a busy background image that will fool OCR attempts.

  2. We can’t forget accessibility questions, like people that can’t actually read this distorted images… it should be implemented with some other possibility, like sound or something…but the solutions presented by now seems great 🙂

  3. joe rinehart says:

    Christian,Strange coincidence – I was putting together a tag-based abstraction of Doug Hughes’s Alagad Image Component to learn his component, and creating a CAPTCHA is one of the examples I’m providing.I’ll be posting about it tomorrow morning on my site (

  4. Dave says:

    PLEASE tell me that last comment was ironic…

  5. James says:

    Very Ironic…

  6. Jake says:

    A bit on topic, maybe off…I’ve been using the cfx_captcha tag for a few months now, to huge success in stopping spam on 4 different blogs – all of which had been hit hard with comment spam.As amazing as this tag is, there’s a few things I’d like to see addressed:- Ability to use no text distortion – just image of text on top of a background. At this point, most comment spammers don’t have the tech to go up against an image of any sort, so massive distortion only irritates users.- Ability to control the placement of the text image within the bounding box of the image. Right now, to get smaller than a certain size on your output image means that, even if you have enough space for the amount of characters you’re writing out, some of the text may get cut off. The 0,0 coordinates aren’t always used for beginning placement. The text could actually start at -20, -40 for instance.Otherwise, great great work.

  7. anonymous says: is a great one…cheap too…you can change the fonts it usesit generates random strings for you(you can specify your own length)

  8. Rob says:

    Isn’t it ironic that I had to ‘solve’ a captcha image to post on this topic but it is not mentioned by the author?

  9. This post was written long before I implemented a CAPTCHA on this site.Christian