Open source is recently much more made and distributed by on-line such as internet in various fields. Therefore, end users could rapidly develop applications needed for some purposes using minimal efforts if use open sources. But, open source must be customized for their purposes. In this paper, we developed software for coordinates conversion and compared the software with NGI Pro which is developed by National Geographic Information Institute. Consequently, it is possible for us to easily develop the coordinates conversion module and we know that the use of open source is effective to develop various applications.