Multi-access Edge Computing (MEC) allows users to run appli-cations on demand near their mobile access points. MEC appli-cations will exploit 5G infrastructure, and they will have to be designed by taking into account the characteristics of 5G mobile networks. This work describes how to use a system-level simula-tor of 5G networks – namely Simu5G, which evolves the popu-lar 4G network simulator SimuLTE – as a real-time 5G network emulator. This allows designers of networked applications – and MEC ones in particular – to use it as a testbed during the de-ployment. We describe the system setup of Simu5G as an emula-tor, and its emulation capabilities and scale. Moreover, we pre-sent a case study of a MEC testbed using Intel’s Open Network Edge Services Software (OpenNESS) toolkit, based on a recent demonstration in 5GAA (5G Automotive Association).