The conceptual model in software development captures the key concepts in specific problem domains, as well as the important relationships between them. The quality of the conceptual model plays an important role for the success of requirements engineering and software development. Generally, the quality of the conceptual model is restricted by modelers' personal knowledge and experience, and a single modeler usually possesses parts of the information that should be captured in a high-quality conceptual model, especially when the problem domain has a high complexity. To address this problem, we developed a tool named SCCMT, which provides an approach to modeling the conceptual model collaboratively with a large number of people, especially an online crowd. The main characteristic of this tool is twofold. (1) An indirect interaction mechanism is proposed to solve the communication problem among the temporal and topographical distributed online modelers. (2) A merge-feedback process is provided to inspire any single modeler in the crowd to improve her/his model based on the current modeling result of the crowd.