Developing countries have economic limitations related to the training, infrastructure, and human resources to develop space technology. Small satellite missions and the use of commercial electrical, electronic, and electromechanical (EEE) components, known as Space COTS, can reduce the cost, time, and gap in space incursions. In this sense, currently, there are low-cost and/or free access tools, especially for the educational sector, which allow the simulation of small satellite missions. These tools include General Mission Analysis Tool (GMAT), OpenApp, and OpenKit. The present work shows the use of these tools and a 3U small satellite mission simulation. It is expected that with the use and dissemination of these tools, more and more developing countries will be able to develop their missions and enter into the space sector.