A lot of cities are working on their digital transformation in order to deliver a better living environment for their citizens. There are many research efforts focused on measuring the performance of such transformation through specific methodologies and indicators covering variety of city dimensions. The complexity of cities as well as the heterogeneity of data that they produced bring challenges to the development of platforms for multidimensional evaluation and smart level assessment of a city. In order to address such challenges, this paper proposes a conceptual data model and an architecture of a platform for performance assessment of smart cities. For assessment of economic performance, 4 indicators are considered to be implemented and are presented in the paper: Gross Domestic Product, New Business Registered, Median Disposable Income and Human Development Index. The proposed platform is designed to be integrated – continuously supplied with city data, scalable – open-ended for implementation of new indicators, multidimensional – designed to cover all city dimensions and agile – evolve in step with the changing requirements.