RTMemController is an open-source tool for evaluating the worst-case and average-case execution time of memory transactions, which are executed by dynamically scheduling memory commands to DDR3 SDRAMs. This tool is based on the dynamic command scheduling algorithm proposed in [1]. It uses the mathematical formalization of the algorithm, which has been shown to produce cycle-accurate timing behavior to a memory controller implementation in SystemC. The following sections introduce how this tool is developed and how to use it to achieve worst-case and average-case execution time results.