This is a comparison of online services which helps to prevent automated abuse of your site (such as automatic comment spam or registrations) by using a CAPTCHA to ensure that only humans perform certain actions.
While these services helps to reduce spam, they will not totally prevent it, since some humans add manually their comments.
These services usually shows a text in an image and visitors must type it to validate the form. To ensure accessibility, some services provide an audio CAPTCHA so that the visitors can listen to it, if they are unable to see the image.
A dedicated comparison has been created for services with
advertisements solutions combined:
|Description||Screenshot||Distinctive features||Multi-language||Visual customization||Audio captcha||Code sample||Wordpress plugin||Compatible SSL||Notable web site using it||Pricing||Free plan||Pricing||Additional||Website||Like|
|AdCaptcher||AdCaptcher enables you to build and monetize custom captchas.||A new monetization method for your websites! Earn revenue by serving smart ads in your captcha.||Yes via CSS||No||Yes||http://www.adcaptcher.com/||http://www.twitter.com/adcaptcher|
|Ads Captcha||ADSCAPTCHA™ offers complete multi-language CAPTCHA solutions, from free security-only CAPTCHAs, to premium CAPTCHAs featuring images and video.||ADSCAPTCHA’s™ innovative Pay Per Type™ platform creates profits from CAPTCHA technology. Instead of paying for CAPTCHAs, website owners and developers can make money from every ADSCAPTCHA™ that is typed in full.||Yes||Yes||Yes||Yes||http://www.adscaptcha.com/|
|Adyoulike||Adyoulike enables a new way of making money using Captchas. Their technology allows you to change the traditional Captcha, difficult to read by an advertising Captcha, nice, easy to read and remunerative.||The Captcha is served as an Ad, so you can get money while securing your forms.||Yes English, French||No||No||Yes||http://www.adyoulike.com/||http://twitter.com/Adyoulike|
|are you a human||It is an alternative to CAPTCHA by using games : humans play but not bots...||Fun way to check that the visitor is an human : he plays a game||No||No||No||PHP, Perl, Ruby, Python, .Net, Java||Yes||Quicken Loans||http://www.areyouahuman.com/||http://twitter.com/areyouahuman|
|Captch Me||Captch Me is an advertising captcha network.||Yes French, English (standard captchas only)||Yes 2 themes||No||PHP, JSP, WordPress, Drupal||Yes||Yes||http://www.captchme.com/||http://www.twitter.com/captchme|
|Captchas.net||Captchas.net servers provides CAPTCHA images and audio files you can use in html-forms to prevent robots from filling it.||Yes Audio pronunciation: English, German, Italian, French, Dutch||Yes Size, color custom design for audio or to refresh the captcha||Yes||PHP, ASP, Perl, Python, JSP, Ruby||Yes||Yes||120 euros per year to remove captchas.net logo||http://captchas.net/|
|NuCaptcha||NuCaptcha provides the only intelligent captcha product on the market today||Behavioral Analysis System that adjusts security on the fly- brandable, SLA, advertising, fully customizable.||Yes Fully Localizable||Yes Skinless version available to fully customize.||Yes||.Net, PHP, Java, various plugins||Yes||Yes||Yes, various, ISP's, VAST and VPAID compliant,||Yes||PRO, ENTERPRISE AND ENGAGE PRODUCTS AVAILABLE FOR SITES WITH MORE THAN 25,000 SOLVED CAPTCHAS PER MONTH.||http://www.nucaptcha.com||http://twitter.com/nucaptcha|
|OpenCaptcha||Does not require any regsitration||No||Yes size||No||PHP||No||No||Yes||http://opencaptcha.com/|
|reCAPTCHA||reCAPTCHA is a free service that helps to digitize books, newspapers and old time radio shows while preventing automatic form filling by robots.||The service helps to digitize books or audio shows||Yes English, German, French, Dutch... (8 languages + custom)||Yes 4 themes + custom||Yes||PHP, ASP, Java/JSP, Perl...||Yes||Yes||Yes||http://recaptcha.net/|
|Solve Media||Solve Media offers the option to implement as security only or monetize the space by allowing advertisements in addition to security.||Fortune 1000 Advertisers | Top tier security (10 levels based on spam activity) | Available for over a dozen languages and platforms. | System detects spam activity and increases security & readability difficult.||Yes English, French, German, Spanish, Italian, Japanese||Yes 4 themes and custom||Yes||PHP, Perl, asp, jsp, python, ruby, asp.net, phpBB, SML, vBulletin, WordPress, Drupal, media wiki, dokuwiki, MyBB||Yes||Yes||Meredith Publishing, Internet Brands, CollegeHumor.com, AOL.com, Vertical Scope||Yes All free||Free to implement.||http://www.solvemedia.com/||http://twitter.com/solvemedia|
|WebSpamProtect||WebSpamProtect.com allows you to add a verification image to your web site forms to protect them against spam robots. The service also provides full contact form management.||Online control panel to customize available captcha, or to create full contact forms.||No||Yes||Yes||PHP, ASP, Perl||Yes||Yes for premium accounts only||Yes||Premium accounts enables SSL access, more customization, and full
|Confident CAPTCHA||Confident CAPTCHA is a picture-based approach to CAPTCHA that asks visitors to click on specific pictures to prove they are human. It is very secure against bots and easy for people to use. Optional advertising feature allows publishers to earn revenue. Confident CAPTCHA is easy to use on smartphones and tablets -- no typing required, users simply click/tap a few pictures to verify.||Highly customizable, mobile optimized, no typing required from users -- simply click on a few pictures. Optional advertising feature allows publishers to earn revenue.||Yes English, Spanish, French, German, Dutch, Russian, and many more languages available.||Yes Administrators can customize the CAPTCHA color, the number of images displayed an the CAPTCHA, the number of images users must click, and many other customization options.||Yes||PHP, ASP, Java, Perl, Python and Ruby. WordPress, Joomla and Drupal plugins also available.||Yes http://wordpress.org/plugins/confident-captcha/||Yes||Yes||Free for up to 50,000 displays of Confident CAPTCHA monthly. Websites requiring more should contact us for Enterprise level pricing. Websites of all sizes can use the optional advertising feature to earn revenue.||http://confidentcaptcha.com||http://twitter.com/confidenttech|
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