Earning the Oracle Application Express 18: Developer Certified Professional certification proves that you are highly competent at developing apps using Oracle APEX. A certified individual has demonstrated fluency in and a solid understanding of the skills required to develop professional apps using Oracle APEX. This includes experience building robust, secure apps that utilize many of the solution's capabilities. This certification is for Application Developers with experience building web applications, which includes Oracle APEX solutions, extending ERPs, opportunistic apps, and more.