[Edit: 2015-09-17] Contact Form 7 4.3 and later recommend reCAPTCHA instead of Really Simple CAPTCHA. For more details, see Contact Form 7 4.3.
Contact Form 7 allows you to insert a CAPTCHA into your contact form to prevent bots from submitting forms. Contact Form 7 utilizes Really Simple CAPTCHA as its officially-sanctioned CAPTCHA module, so you will need to install the Really Simple CAPTCHA plugin before you use CAPTCHA in your form.
The rest of this article will explain how to use CAPTCHA with Contact Form 7, based on the assumption that you have already installed Really Simple CAPTCHA.
Before using CAPTCHA
Really Simple CAPTCHA requires that GD and FreeType PHP libraries be installed on your server in order to create CAPTCHA images. If you are not certain if they are installed, ask your server administrator.
Contact Form 7 creates a temporary folder and stores any CAPTCHA files there. In most cases, the location of the temporary folder is wp-contents/uploads/wpcf7_captcha, but it can be different depending on your settings.
This folder is created automatically, but sometimes it can fail. A possible cause for this is that the parent folder doesn’t have sufficient writing permissions. In such cases, you can change the permissions or create a folder manually.
You can also change the path of the temporary folder by setting the WPCF7_CAPTCHA_TMP_DIR constant in your wp-config.php like this:
define( 'WPCF7_CAPTCHA_TMP_DIR', '/your/file/path' );If WPCF7_CAPTCHA_TMP_DIR is defined, this directory is used as the temporary folder instead.
Make certain your temporary folder for CAPTCHA files exists and is writable. Otherwise, CAPTCHA can not be created.
Selected gd extension in your php version:
