In this thesis, we present C API programs which are capable of interface PHP programs to C-language programs. Using C API programs, we can develop web-based Solvers which provide conveniently solutions for the programs such as sorting programs, optimization programs, statistical analysis programs on the Web-site. And C API problems also provide users with effective data utilization on the different operating system, that is, 'Windows 2000' used for web server and 'Linux server' used for database server. Processing with C API, the flow of data on the different operating system become more economical and useful. Two examples, including a sorting program and a NRO(Network Reliability Optimizer) program, are given in this paper. The further study is constructing more user-friendly environment on the Web-site.