Researchers share large amounts of digital resources, which offer new chances for cooperation. Collaborative annotation systems are meant to support this. Often these systems are targeted at a specific task or domain, e.g., annotation of a corpus. The DWAN framework for web annotation is generic and can support a wide range of tasks and domains. A key feature of the framework is its support for caching representations of the annotated resource. This allows showing the context of the annotation even if the resource has changed or has been removed. The paper describes the design and implementation of the framework. Use cases provided by researchers are well in line with the key characteristics of the DWAN annotation framework.