Techniques are disclosed relating to an in-memory, software-managed cache configured to store web application data. In some embodiments, operations to cache data specify a visibility parameter for the data, among a plurality of namespaces. In some embodiments, requests to access cached data are checked, based on a request's namespace and the visibility parameter for the cached data, to determine whether they are allowed to proceed. In some embodiments, this may facilitate caching data using shared computing systems and data structures while maintaining configurable privacy for cached data.