We present an open source software, named as TrajAnalytics, which models, transforms, and then visualizes urban trajectory data for transportation and urban study. It allows researchers, administrations, and practitioners to understand the population mobility data and to discover knowledge intuitively. A conceptual data model is presented which integrates trajectory data with geo-structures through a variety of data access queries. The model guides us to develop data processing and management capability and support various visual queries through a Web-based visualization interface. A set of visualization widgets and interaction functions promote easy user engagement. A primary user study shows the usability of the software.