Adding re-captcha in your site. You have two options the basic and the google re-captcha.
For basic captcha; no need to register in google. we maximized the use of basic opencart captcha
For Google reCaptcha; simply copy and paste your key and secret key code in the admin area.

Works also for Jcart version 2.x.x.x and Mijoshop Joomla 3.x.x component (Joomal 1.5, 2.5 and 3.x).

For OpenCart : (Opencart 2.0.0.0, 2.0.1.0 and 2.0.1.1 - Compatibility)

Live Demo Click Here