In open Multi-Agent Systems, norms are being used to regulate the behavior of the autonomous, heterogeneous and independently designed agents. Norms describe the behavior that can be performed, must be performed, and cannot be performed in the system. One of the main challenges on developing normative systems is that norms may conflict with each other. Norms are in conflict when the fulfillment of one norm violates the other and vice-versa. In previous works, the conflict checkers consider that conflicts can be detected by simply analyzing pairs of norms. However, there may be conflicts that can only be detected when we analyze several norms together. This work presents a complete approach for conflict detection and conflict resolution among pairs and multiple norms. The strategy for conflict detection is divided into three steps in order to smooth the computational cost since the problem is intrinsically exponential. The strategy for conflict resolution applies famous strategies found in literature to rewrite or remove conflicting norms. The paper describes a tool, named Multiple Norms Conflict Checker Tool (MuNoCC), that integrates different screens for conflict detection and resolution. This approach works as a basis to assist MAS literature, defining norms formally, checking conflicts among pairs and multiple norms and resolving the conflicts found.