Captcha & Re-Captcha in WordPress (with samples)

What is captcha?

A captcha (Completely Automated Public Turing test to tell Computers and Humans Apart) is a program that can generate and grade tests that humans can pass but current computer programs find hard.

How does a Captcha work?

It is usually an extra field to a web form that asks the user to complete a simple task such as reading an image or understanding a simple question.  Automated programs that attempt to “hack” the form find these questions hard.

How does a Captcha reduce spam?

Adding this to the email contact forms on your site will prevent some of the spam generated by automated software programs designed to crawl the internet and fill in forms. Unlike a human, the software would be unable to pass the test and so you will get less spam enquiries.

How does a Captcha help with security?

Similarly adding one to a login or sign up form will help reduce automated hacking attempts.

What is Google Re-Captcha?

Re-Captcha is a special Captcha that aids the digitalisation of books to help with words that the software used in digitalising books cannot “read”.  You can find out more at The functionality of the re-Captcha is provided for free by Google.

Is adding a Captcha worth while?
Do Captcha’s work?  Why bother with a Captcha at all? 

Captcha’s are not perfect, they can be beaten.  However, like ALL other security measures they increase the effort an attacker must put in.  The goal is to make that barrier so high that it’s not worth the huge effort required to “break in”, while keeping a balance with usability (a badly implemented captcha is really annoying).

Therefore, they can be a useful tool, especially if you do receive spam from your contact forms.  However it should only be considered in relation to a well developed web site and good security practices generally.

Captcha samples and examples of different types

Examples of image captchas:

Two Example Image CaptchasSample Image Captcha

Examples of simple maths captchas:

Sample_CommentsForm_Captcha Sample_Maths_Captcha

A reCaptcha sample:

Recaptcha example

Captcha’s and WordPress

There a number of plugins that make it easy to add captchas or recaptcha to your wordpress site.

For further advice or to implement any of this on your WordPress site don’t hesitate to get in touch!


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