Embodiments of the systems described herein can implement one or more processes remotely delivering customized code to a host application and/or computing device. The host application may be configured as an Application Programming Interface with a customized code processing library that may configure the host application to receive further instructions remotely. The host application may be further configured to execute host code and/or third-party code. The host application may be configured to receive remote application logic, after the host application has been installed on a computing device, and to execute the received application logic to alter the behavior of the host application, such as selectively tracking end user interactions.