Software developers need to cope with the complexity of Application Programming Interfaces (APIs) of external libraries or frameworks. Typical APIs provide thousands of methods to their client programs, and these methods are not used independently of each other. Much existing work has provided different techniques to mine API usage patterns based on client programs in order to help developers understanding and using existing libraries. Other techniques propose to overcome the strong constraint of clients' dependency and infer API usage patterns only using the library source code. In this paper, we propose a cooperative usage pattern mining technique (COUPminer) that combines client-based and library-based usage pattern mining. We evaluated our technique through four APIs and the obtained results show that the cooperative approach allows taking advantage at the same time from the precision of client-based technique and from the generalizability of library-based techniques.