A CAPTCHA is a tool designed to prevent spambots from sending unsolicited messages by requiring users to complete a challenge before submitting an online form. There are a number of different CAPTCHAs you can use to deter spammers, and you’re probably already familiar with conventional math-based challenges which require you to perform simple addition, or ReCAPTCHA which uses distorted text to stop spam.
If you use a content management system, you can find lots of free CAPTCHA plugins, extensions, and modules for WordPress, Joomla, and Drupal. While many of these plugins use traditional challenges, I’ve found some CAPTCHA extensions and modules which use unique and even fun methods to stop spammers.
Some of these CAPTCHA plugins, extensions, and modules use image challenges which require people to click the correct photos or solve a puzzle, while others are text-based riddles or fill-in-the-blanks. I’ve even found some modules, extensions, and plugins which feature advertisements in CAPTCHAs, so you can earn some extra income every time someone submits a form or comment!
WordPress CAPTCHA Plugins
With this free WordPress plugin, your website’s users will be prompted to click on the correct image before they can submit a form, comment on a post, register with your site, or complete a poll or survey. Plus, you can configure the number of images your users must choose from, as well as the number of images they have to click to verify they’re human. Due to its intuitive design, your users will find Image-Based CAPTCHA very easy to use, making it a great way to prevent spam without frustrating genuine visitors.
Another option for preventing spam is Ironclad CAPTCHA, a WordPress plugin which uses 3D objects to validate users. Before successfully submitting a comment, your visitors are presented with a CAPTCHA which consists of multiple 3D objects. Users are asked to enter the number of times a particular object, such as a key, appears.
If you want to try this plugin but you don’t use WordPress, then check out the free Dreamweaver version of this plugin!
With this free WordPress plugin, you can earn ad revenue while protecting your website from spammers! Before your users can successfully submit a comment, contact, or registration form, they are presented with a simple CAPTCHA featuring an advertisement. Each time one of your site’s visitors solves a CAPTCHA, you will receive a share of the ad revenue, making it a great plugin for bloggers who need to make a bit of extra cash.
This free WordPress plugin offers a fun, interactive, and user-friendly way of preventing spam! This CAPTCHA asks your users a question, and they simply have to drag the image of the correct answer to prove they’re genuine. Sweet Captcha offers lots of different design categories to choose from, including movies, music, and wedding, and you can even create a custom CAPTCHA for your site. This plugin is compatible with mobile devices, it includes translations files for several different languages, it can be used for various types of forms, and it even works with BuddyPress, making it a great anti-spam tool for loads of users!
Another alternative to traditional anti-spam tools, KeyCAPTCHA is a free WordPress plugin which requires users to perform a task or assemble an image before they can successfully submit a comment, registration, contact, login or lost password form. KeyCAPTCHA is compatible with multiple browsers, as well as iPads and iPhones, and it works with BuddyPress, making it a versatile spam prevention tool. Plus, if you join their affiliate scheme, you can earn income from the advertisements placed in the KeyCAPTCHA on your site.
Joomla CAPTCHA Extensions
This free CAPTCHA extension for Joomla requires user to either match images or select the correct label for a photo before they can successfully submit contact, registration, forgotten password, and custom forms. Peoplesign photo captcha offers tons of customisation options, including the number and size of photos, various messages for users, the colour scheme and design, and even the ability to use distorted images for challenges. This extension is very easy to install and configure, and your site’s visitors should find it simple and fun to use.
Another anti-spam tool for Joomla is KeyCAPTCHA, which requires users to complete a puzzle before they can submit various online forms. This free CAPCTHA system is compatible with a number of popular Joomla extensions, including VirtueMart, K2 Comments, AdsManager, JWHMCS inegrator, Community Builder, JComments, and loads more. Plus, you can sign up to KeyCAPTCHA’s affiliate program and earn money by including ads in the CAPTCHAs on your site.
Drupal CAPTCHA Modules
This free Drupal module helps prevent spam by requiring users to click the correct image or images before they can submit forms, post comments, register accounts, or answer polls and surveys. Image-Based CAPTCHA offers a number of customisation options, so you can easily control how many images are displayed, the number of photos a user has to click to verify they’re human, and the background colour. This Drupal module even offers audio verification for visually impaired users, so all of your site’s visitors should find it simple to use.
With this free anti-spam tool for Drupal, users are presented with a simple phrase missing a verb, and they have to enter a word to complete the sentence. Unlike more conventional CAPTCHAs, there are multiple correct answers for each challenge, making Egglue CAPTCHA intuitive and easy to use. This free Drupal module uses the Egglue Semantic CAPTCHA service to generate thousands of different challenges, making it an effective tool for deterring spammers.
This free Drupal CAPTCHA module enables you to create custom questions your site’s visitors have to correctly answer before they can submit forms. With Captcha Riddler, you can have more than one right answer for a single question, and the language settings will determine which questions are displayed. This Drupal module is a great way to showcase your sense of humour or interests to your website’s visitors while preventing spam.