I just got an e-mail from someone saying that my homegrown CAPTCHA was “stupid”. On the contrary, it’s far more effective than Google’s.
On one of my other web sites, PCBShopper.com (a price comparison site for printed circuit boards), I have a contact form with a CAPTCHA I made myself. It simply asks “What does the B in PCB stand for?”
My correspondent, who was also insulting other things about my site and chose to remain anonymous, thought this was a stupid CAPTCHA. But it’s 100% effective, it filters out spam that Google’s CAPTCHA lets through, and nothing short of IBM’s Watson can crack it (even Watson might fail if it thinks PCB is referring to polychlorinated biphenyl instead of printed circuit board).
Obviously, no general purpose spambot is going to be able to answer my CAPTCHA. But what’s even better is that a lot of humans can’t answer it either. I used to get a lot of spam from people offering to redesign my web site or boost my page rank in Google. And the spam really was from people – they were able to solve Google’s CAPTCHAs. But they didn’t know what a PCB was and were not going to take the time to figure it out. And so I stopped getting that spam. (Like I want someone who doesn’t know what a PCB is, to be redesigning my web site!)
As far as I’m concerned, if someone doesn’t know what a printed circuit board is, I don’t want to hear from him on PCBShopper.com.
Yet another one of my sites is Vectrex32.com. The Vectrex is a gaming console from the 1980s. My CAPTCHA there is “How many buttons are on a Vectrex controller?”. If someone doesn’t know the answer, there’s no good reason for them to be contacting Vectrex32.com. My ByteCovers.com (dedicated to the beautiful paintings that graced Byte magazine’s covers) asks “How many bits in a byte?” Again, not a single spammer gets through, but anyone who is nerdy enough to know about Byte magazine will know the answer.
I highly recommend such domain-specific CAPTCHAs. They’re better than Google!
Yes, they’re better. At least as long as you’re the only one doing them, and automated CAPTCHA breakers don’t have much incentive to break them.
But Google’s CAPTCHA serve an additional purpose – they train machine learning algorithms. So they serve two useful purposes at once – filtering spam and teaching machines to understand images. Yours only does the first. From a purely self-interested view I suppose you don’t care.
(Plus, every time I try to solve your CAPCHA here, I get “time limit exhausted” unless I manually reload the page. I think you have a bug. As if extra time would help people break yours – I think you can safely drop the time limit completely.)