Mental health indicators are essential for monitoring people’s mental health status, developing mental health policies, and evaluating the performance of such policies. The aim of this paper is to describe the development of a web-based tool for mental health indicators capable to support the management of Brazilian mental health care networks. The SISAM is a web information system responsible for management and provision of mental health information in Brazil and it was chosen as the use case of this study. The indicators were developed as a decision support web tool for public health managers. The tool is able to calculate 11 indicators related to inpatient care. A descriptive analysis of all indicators is presented using SISAM data from 2017. The results generated by the tool are promising and could provide improvements on care monitoring, evaluation of possible trends and investments in prevention and promotion in mental health care.