Ranking is necessary for multiplayer online games to provide players with self-complacence and reference for choosing game counterparts. Most existing ranking solutions are tightly coupled with game applications of client-server architectures. In this paper, a novel scheme named FreeRank is proposed as a ranking service independent to specific architecture and detailed implementation of each individual game application. Based on a certificate-based framework and a reputation-based score-computing algorithm, FreeRank resolves the challenge of cheating prevention. Preliminary analysis and simulation results show that FreeRank is feasible and effective. Categories and Subject Descriptors K.8.0 [General]: Games, C.2.1 [Network Architecture and Design]: Ranking Service. General Terms Management, Design, Security Keywords Multiplayer Online Games, Ranking Service, FreeRank