The proliferation of Internet of Things (IoT) technologies in various industrial sectors has brought forth new challenges that demand attention for achieving technological maturity. One such challenge is the lack of tools for emulating the diverse components present in IoT architectures, leading to the continuous verification of each component in the chain, which proves to be a complex task. This paper addresses the verification problem in Edge/Fog IoT platforms through comprehensive end-to-end testing. To tackle this challenge, we have developed a modular IoT simulator (SimIoT) capable of efficiently emulating thousands of IoT devices in realistic scenarios, including hospitals, airports, and smart cities. The simulator allows testing of Edge platforms without the need for programming expertise. Furthermore, we demonstrate the feasibility of our simulator by presenting a use case involving the profiling of an open-source IoT platform.