I'm sure you all are as tired of the occasional spam that hits these lists as I was deleting it. (Mailing list users in particular, I guess, since we can't delete an email once it was sent out.) Most of the spam was coming in through the forum, so I suppose I was responsible for [not] keeping it out.

Although forum.dlang.org has had a spam check and used reCAPTCHA since it was announced, it is only somewhat effective against fully-automated bots - it is powerless against humans paid to post spamverts on forums web-wide, which is what the current spam economy seems to be gravitating towards.

Enter DCaptcha, a question-answer challenge tailored for D programmers. Its goals are to challenge posters of suspicious-looking content with questions that should be easy to answer to D programmers, and impossible for non-technical people with no incentive to learn or research stuff (i.e. spammers). DCaptcha is already in use on the D wiki (wiki.dlang.org), with great success - DCaptcha's debut cut the short-lived explosion in wiki spam to zero.

For an idea of what sort of questions DCaptcha asks, you can demo it on the following page, so you don't have to clutter the forum with test posts:


Source code:


Pull requests for more challenges are welcome. You can find some goals for new challenges at the top of dcaptcha.d.

Previous discussion (w.r.t. the D wiki):


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