A customized library management method and system generates a customized class library needed for executing an application in a client system. In response to an identification of a given application, the server determines the appropriate classes and methods to include in a library to be sent to the client based on certain parameters. The customized class library includes classes that are required by the application and that are not yet loaded on the client. The requested application and the customized class library are then transmitted to the client for execution. Within a customized class library management system, a client system can deflate, delete and regenerate applications and class libraries in accordance with resource requirements of the client and other criteria.