The development of smart cities requires a broad digital network, technology infrastructure, services, creativity and innovation. These are all important components of an ecosystem that offers a better quality of life to society. However, to develop systems to be part of the smart city, it is necessary to understand the challenges and opportunities involved on it, especially the informal systems that are used by citizens and do not belong to the formal structure of public administration. Informal systems are created to meet the needs of citizens. As such, this work aims to present challenges and opportunities identified in this scenario. The method adopted to increase information on this topic was an online survey research. As a result, “transport” was highlighted as the most cited opportunity and “lack of investment” as the most cited challenge to be overcome according to the participants. As a contribution, a discussion about the results is carried out and allows the analysis of the identified opportunities and challenges so that professionals can take advantage and develop systems that citizens recognize as necessary to make a smart city.