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Impossible CAPTCHA : It Doesn’t Really Matter if You are Human or Not

CAPTCHA galleryCAPTCHA is an acronym for “Completely Automated Public Turing test to tell Computers and Human Apart”. In a broader sense, CAPTCHA is defined as:

Type of challenge-response test used in computing to ensure that the response is not generated by a computer. The process involves one computer (a server) asking a user to complete a simple test which the computer is able to generate and grade…

[“simple” is the key word here]

CAPTCHAs present a very controversial topic: you can’t do without them as a webmaster and you can’t stand them as a user.

Some CAPTCHAs are just impossible to figure – no matter who you are (a robot or a human), you won’t pass the test. Here’s my gallery of impossible CAPTCHAs:

Read fast:

Impossible captcha: The Matrix captcha


Find cats:

Impossible captcha: find th cats

Source: Depressed Programmer

Train your imagination:

Impossible captcha: unfold the patterns


Learn other languages:

impossible captcha: international symbols


Look for the hidden code:

Impossible captcha: hidden code


Just guess:

Impossible captcha

(The second character cannot be figured I guess)


Impossible captcha: no text

(Do you see text at all?)


Know your 1-2-3:

Impossible captcha: math


Post image: Geek and Poke via Search Engine People

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  1. 45 Responses to “Impossible CAPTCHA : It Doesn’t Really Matter if You are Human or Not”

  2. Just gread – love those with the big math challenge.

    By Tobias on May 18, 2009

  3. Ann,

    Funny gallery of impossible CAPTCHAs. I did a post on this exact topic back in December title Is Your CAPTCHA Killing Your Business?

    Definitely the CAPTCHA is one of my biggest pet peeves when it comes to usability.

    Thanks for the amusing post. :-)

    By Gerald Weber on May 18, 2009

  4. Ann, this is an awesome killer post… had 7 retweets of my tweet within minutes :)


    By Christoph C. Cemper on May 18, 2009

  5. The last mathematical capture is probably 0. Since inserting the value of pi for x gives numerical values for sin and cos not terms in x. And partial differential a number w.r.t. x is 0.

    P.S. The 2nd character in the 3d. landscape looks like an N to me.

    Nice capcha examples, great post.

    By ned on May 18, 2009

  6. Whoops my mistake. x=Pi is after the partial differentiation.

    By ned on May 18, 2009

  7. 480.

    By Manley on May 18, 2009

  8. Ann!
    I’m surprised to your finds again and again.
    They looks so simple but very interesting.
    I think that is a really killer post.
    Twitit and bookmark it on Delicious.

    By seobag on May 18, 2009

  9. 42!

    By Karl on May 18, 2009

  10. I got number 5 its one of those magic eyes
    it says 438
    magic eyes are fun but not everyone can do them…not so good for business…lol

    By cybernautSEO on May 18, 2009

  11. Hi Ann,

    Hysterical! Thanks so much for finding these. Given our line of work, I’m always collecting funny and impossible CAPTCHAs. The Matrix stream and 3D terrain are among my new favorites!

    You’re also right that it doesn’t matter if it’s a human or bot doing the submitting, but not necessarily because the puzzles are too complex. In the past few years spammers and hackers have started hiring teams of workers to submit spam/abuse to Web forms for pennies (even for forms that don’t use any kind of CATPCHA).

    If it’s humans submitting spam anyway, why bother trying to distinguish computers from humans? Ah, the irony. 😉

    Thanks for a fun post!

    By Larissa Reynolds on May 18, 2009

  12. The formula on know your 123 is 6. Wolfram Alpha has a use afterall. :)

    By Ned on May 18, 2009

  13. Hey Ann! Would love to post this directly into facebook… where is your facebook app? ShareThis is really exceptional for ease of posting :)

    By Dianna Kersey on May 18, 2009

  14. Wow what an unusual collection. I have never come across most of these captures before – very amusing!

    By Mandy on May 19, 2009

  15. I have a more interesting captcha, I hope.

    Try a few times, the animals change:

    By Manley on May 19, 2009

  16. What a funny article! But I like it very much. Would let me introduce it on my blog(Japanese)? I’m sure to give credit to you and put a link to the post there.

    By Kenichi Suzuki on May 19, 2009

  17. What a funny article! But I like it very much. Would you let me introduce it on my blog(Japanese)? I’m sure to give credit to you and put a link to the post there.

    By Kenichi Suzuki on May 19, 2009

  18. these are great – never could see the hidden code

    By Zion on May 19, 2009

  19. @Manley, yeah, yours looks great! But it is not impossible though :)

    @Kenichi, sure, no problem

    By Ann Smarty on May 20, 2009

  20. Are you kidding?

    Who can read those.

    On a more serious point… do you think that adding a captcha stops people from responding.

    I know it only takes a few seconds to type in an easy to read one, but I’m sure some people can’t be bothered and your website misses a potential sale or contact.

    Thanks for the examples.


    By Bill Simcox on May 21, 2009

  21. i had faced many probs filling CAPTCHA its really an eye teaser..

    By SixChannels on May 22, 2009

  22. @Bill, the short answer is “yes” – CAPTCHA does provide some usability challenge. Unfortunately, we seldom can get along without it. A good way out is to make it entertaining like the one linked to in the comment above:

    By Ann Smarty on May 22, 2009

  23. There may be a fun marketing angle here, especially for small niches. Especially if these form submissions wouldn’t be for lead submissions from potential customers.

    Maybe registering for an event would require a fun or specific question. An example would be an elite math club might require an equation to be solved.

    By Jesse Friedman on May 27, 2009

  24. Ironic that the first post I read on Sphinn is this – registering with that site required a simple sum AND a character captcha and was so unclear it took 3 attempts to get past!

    By Andy on May 28, 2009

  25. That’s too funny. I understand CAPTCHAs are necessary, but some of them are hard to read!!! Hopefully someone can come with a decoder ring or some glasses for them soon.

    By MLDina on Jun 1, 2009

  26. In the meanwhile I am using Twitter’s CAPTCHAs to name the songs on my upcoming album.

    Annoying or not they are already a part of our life :-)

    By fjfonseca on Jun 4, 2009

  27. There is very interesting, there is very fun.

    By TiamatInc on Jun 4, 2009

  28. This is a GOOD one Ann! SOme of these they are coming up with will make you crosseyed. 😎

    By Seo Consultant on Jun 5, 2009

  29. I got number 5 its one of those magic eyes
    it says 438
    magic eyes are fun but not everyone can do them…not so good for business…lol

    By Sohbet on Jun 17, 2009

  30. Its a thin line between stopping your hassle and killing any user interaction completely. Comments and signups cannot be without any work or moderation can they, thats life!

    By paul on Jul 9, 2009

  31. Cool! I saw the CAPTCHA Cats. It’s in, but their deactivated it. I believe that was because of the difficulty!

    By Mike on Jul 15, 2009

  32. LOL these are just too funny – thanks a lot for the list.

    By fan on Jul 15, 2009

  33. Most of them cannot be passed, I suppose

    By Aaron on Jul 15, 2009

  34. So true.. I have been fighting with my dev team on removing captcha from landing pages too.. I told them I myself have hard time reading it.. but they think tht am just making it up.. neways..

    things apart.. i loved that u have a category called SEO Ethics.. 😛 Kudos for that

    By Sandeep Bali on Aug 3, 2009

  35. So true…I recently was requesting service from a website and I could not get the captcha to work. After leaving with a serious ding to my self esteem (turns out I’m not human). I emailed them. Never heard a response, guess I will go with someone else.

    By Jason Capshaw on Aug 13, 2009

  36. Hey Ann,

    Such good finds. =)

    These captcha’s are really very impossible most of the times… It’s actually sometimes becoming irritating.

    Another one good post from you.


    By Bennie Stark on Aug 20, 2009

  37. The cats one is easy.

    But I simply cannot do the Magic Eye things. Never could.

    By Nulono on Sep 26, 2009

  38. This CAPTCHA is impossible. This is very bad for site.

    By Panica on Oct 15, 2009

  39. i lived a very bad day because the first captcha you mentioned (that one of the cats) .it used on rapidshare i have to download a very important file to complete my research. and my supervisors keep asking about the results and i spend the whole day tring to solve this captcha with no hope until i called the lap in the uk to send me another copy of the file
    if i can catch the developer who developed this captcha i would kill

    By ahmed on Nov 1, 2009

  40. Good Stuff. Some hard to read Captchas are so very annoying.

    By Dallas SEO on Mar 29, 2010

  41. I’ve come across some like this including ones that were in letters and sybols. Some I didn’t even have on my keyboard

    By doctor carter on Aug 29, 2010

  42. Funny Post…

    The one that looks like a calculus captcha is nuts! I have seen something similar trying to joining a money forum, but that’s beyond what I experienced there.

    By Dallas TX SEO Consultant on Mar 3, 2011

  43. You know what’s interesting? Captcha is designed to not be passable by a computer (hence how it tests your human-ness) and yet the computer must know the answer as it is the very thing that is assessing your Captcha test. In case you’re curious I wrote a post about the philosophy of Captcha here
    Let me know what you think!

    By Michael Cunningham on Mar 3, 2012

  44. My problem is that when it is straightforward to copy, the app itself malfunctions, too often. Reading it correctly can be one challenge.
    But when the combination of Arabic numerals and Capital letters is plain and unadorned and multiple tries still don’t work, it’s a common malfunction of a badly coded app.
    I tried last night to Contact Us to let them know that Captcha wasn’t working on their Site. Captcha blocked my letter of complaint about it.

    By PreachJohn on Mar 8, 2013

  45. An impossible captcha proves to me the site only cares more about it’s few loyal readers then it does of capturing new audiences.

    I give the friendly back arrow a hard click and make a note of myself never to visit any blog that is hosted by that site.

    For example Soft Pedia has an impossible captcha asking you to solve an equation but then there is another number that has nothing attached to it that I don’t know what it’s there for unless I am not seeing something.

    By SortingHat on Apr 13, 2015

  46. Instead of making any real effort to stop spam the US Democrats just want to take freedom away by robbing Peter to pay Paul while turning a blind eye to the real problems.

    Saturday Night Live which usually is a Liberal show actually made fun of Hillary Clinton non stop for several hours having entire specials about her to make her look stupid.

    One of the Conservative talk shows mentioned it and I couldn’t stop laughing.

    By SortingHat on Apr 13, 2015

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