Do you know about “Completely Automated Public Turing test to tell Computers and Humans Apart,” terminology? If you are a blogger then you must have used this in your various projects, while designing a contact form, login form or any other type of registration forms.
Still unable to figure out what it is. Ok, just focus on the initials of the words. Yes! It is CAPTCHA!
CAPTCHA is an easy method, which are designed to differ between human and bots or malicious software to keep them away. CAPTCHA helps to curb the unethical activities and to give the spammers a hard time.
Since 2000, when the term was first coined it has helped millions of bloggers and webmasters to keep their blog clean. Below is the list of 21 such scripts and services, which help you in avoiding spam:
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reCAPTCHA
A very useful plugin which easily differentiates between human and bots. It is used at all places where genuine registrations or human participation is required.
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WP Captcha-Free
Another captcha which produce a token on the basis of user IP address, post id and browser user agent. The use of Ajax makes this process possible.
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Akismet
A very well known spam control plugin for wordpress users. All those bloggers who use WordPress for their blog must be thankful to the efficiency of Akismet in distilling out actual comments from spam.
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Securimage CAPTCHA
A PHP supported captcha which works on all browsers and pages, as far as they are PHP based. A free captcha script, which can be easily embedded in existing pages to make them safe from any abuse.
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Defensio
A spam-filtering program, which is used to keep your web application and blog safe from unwanted spams.
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WebSpamProtect
Pages that are made on PHP, Perl, ASP or ASP.NET can be easily protected by putting a small code within the page code. Webspamprotect generates a verification code, which keeps spam bots away.
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Mollom
A moderator of your blog, web site or web application against unwanted comments.
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CryptograPHP
A PHP script that automatically generates random numbers, numerals or mix of both. This stops spam bots from intruding your website/application.
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Vidoop
An image based captcha where the user does not have to type any verification code, but identify the correct image in order to pass the verification.
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Protect Web Form.com
Protect your guestbook, feedback form, comment form and any other web form with free anti-spam service of verification urls.
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identiPIC
A photo CAPTCHA system whereby a website visitor has to identify a picture to proceed and verify that he/she is not a bot but human.
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ASIRRA
Asirra partnered with petfinder.com is image-based captcha, which ask user to identify the image of the pet.
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OpenCaptcha
To protect you from the trouble of filtering spams from actual comments OpenCaptcha.com provide a simple set of code, which is just needed to copy and paste in your form code or anywhere you wish to use.
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captchas.net
CAPTCHA images and audio files that you can use in html-forms. CAPTCHA images prevent forms to be used by robots and keep your mail box clean.
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Ironclad CAPTCHA
Integrate a given code inside your PHP or ASP.NET application. A 3-D image generates, which is very easy for a human being to identify and equally difficult for a bot to clear the test.
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Snaphost: Free Captcha form-to-email script
Without any technical skill you can easily install this captcha code in your registration forms, contact forms or blogs and keep bad bots away.
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Spamerator.com
Avoid automatic robotic registration of your registrations form, forum posting, comment posting, etc, as they are futile to your objective. Spamerator gives a captcha solution to avoid junk mails and unnecessary brimming of your mail box.
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Text Disguise
Automatic generation of images to verify the user as human or robot.
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Captchator
Captchator is an easy to install captcha code and also works on shared hosting accounts.
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BotDetect CAPTCHA
BotDetect CAPTCHA is an awarded website security solution designed to prevent automated page posting with Captcha images. While computer programs cannot read the textual code from the image, it is easy to read for humans.
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Puremango: free PHP CAPTCHA v1.4.1
A script to stop spam and keep you trouble free so that you can utilize your work.
Share your favorite:
Please write about your favorite one and the reason why you like to work on it. In addition, feel free to leave any constructive comment about any application.
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I have been searching for a fully accessible CAPTCHA which would, instead of relying on recognition of an image or text in an image, simply ask a common sense question in plain text which a human could easily answer but a machine could not. Do you know of any such service?
Good list, we use reCaptcha and Akismet for our sites, they work well.
Wow, I didn’t even know there were so many options.. thanks for this article!
[...] 21 Best CAPTCHAs: Bloggers Boon & Spammers Bane [...]
Awesome post for designers. Very resourceful. Thanks for sharing this nice post.
[...] 21 Best CAPTCHAs: Bloggers Boon & Spammers Bane [...]
21 Best CAPTCHAs: Bloggers Boon & Spammers Bane…
Do you know about ?Completely Automated Public Turing test to tell Computers and Humans Apart,? terminology? If you are a blogger then you must have used this in your various projects, while designing a contact form, login form or any other type of reg…
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I had no idea there were 21 different captchas out there. And this site doesnt even use one? Weird.
@Matthew Good question, the reason we are not using any captcha form in our comment section is that we have been receiving gentle comments like yours so far. Also, we have been using Akismat plugin to filter the spam comments (if any).
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Very good concept, I like how you convey the message.
reCAPTCHA is my favorite by far! It is easy to implement, plus you get a good feeling from helping to digitize old books.
Hm… From the list the reCaptcha is the best one i think.
But, as i’m a developer, i prefer using my own class for human-detection
http://chargedweb.com/labs/files/CaptchaValidator.swf
Thanks you as a service to the wonderful information.
The information here is great. I will invite my friends here.
Thanks
Very nice Blog, I will tell my friends about it.
Thanks
I absolutely adore captchas:) Makes our life much more fun and easier!
I just like the style you took with this topic. It isn’t often that you just find something so to the point and enlightening.
Nice article. Thank you for this info
Nice post…Thank you for sharing some good things!!
nice share, good article, very usefull for me…thanks
WP Captcha is the most popular I think.
The Vidoop CAPTCHA listed (#9) has been acquired and approved upon by Confident Technologies. It’s a free web app and it’s by far the easiest on your website visitors while also being more secure than text-based CAPTCHAs (which can easily be solved by bots using optical character recognition).
The former Vidoop CAPTCHA, now Confident CAPTCHA from Confident Technologies is available for free here: http://demo.confidenttechnologies.com/captcha/