WordPress.org

Add an verification code when user posting a comment to keep robots away. You can use an image verification code or a math equation instead.

Robots may post lots of spam comments into your database. You can add a verification code image or a math equation to avoid this.

Features:

• You can choose a verification code image or a math equation as you wish
• You don't need to edit any source code of WP, you just need to active the plugin