In typical open source software development, developers use revision control systems for product management, mailing list systems for human communications, and bug tracking systems for process management. All of these systems store development histories of the products that show significant information of problems during the development.However, it would be a hard job to retrieve useful information related to a current problem faced by developers. In this paper, we describe a software development supporting system CoxR that is capable of crawling the development histories. CoxR creates software development information web which consists of developers, emails, and program deltas, and provides an interface to search, navigate, browse, and retrieve past development results. Through a case study, we confirmed that CoxR helps developers to solve their problems by making it easier to search development history.