A software resource manager is stored on a client computer and maintains a map of unique identifiers to resources, so as to determine those resources that are stored locally on the client computer and those resources that must be retrieved from a server system. The resource manager is further programmed to either pass the resources to one or more software applications, e.g. a toolbar application, or respond to a function call from the software application indicating that resources are needed. In this way, one or more software applications can be internationalized or customized without the need to distribute all of the resources for the application and without the need to restart the application.