A method and system for versioning of applications is provided. A version of an application may be updated or rolled back transparently to the client. A list of resources in a current version of an application is created and compared to the list of resources in a new version. When a resource is not included in the current version but is included in the new version, a notation is made to include the resource in the new version. When an extra resource is in the current version but not in the new version, a notation is made to purge the resource so that it is not included in the new version. These notations may be created in a purge list used by the client to request the resources needed to change versions. No interaction is needed by the client to change versions.