FELIB provides software components for flow measurement engineering. We transform the corresponding international standards and procedures into executable programs, c-codes and dynamic link library components (DLL), which can be easily incorporated into the new developments. FELIB software facilitates the calculation of fluid properties (natural gas, oil, water and steam) and the engineering of flow measurements, as well. By combining FELIB components, the complex measurement systems can be developed. Currently, we offer a complete library of software components for flow-rate measurements and engineering based on pressure differential devices (orifice plates, nozzles, Venturi tubes and cone meters) as the most widely used devices in industry. You can download and install demo versions of our executable programs.