A tag management system for a user of a client-side portal application providing access to a set of services that include provisions for collaborative tagging of content comprises one or more data repositories configured to maintain one or more separate sets of tags, a messaging intermediary configured to provide access to the one or more data repositories and to provide for communication with the set of services, and a client-side agent configured to communicate with the set of services and access the one or more data repositories through the message intermediary to act on instructions provided by the user in one or more user roles. A set of tags corresponds to each service in each user role and specifies an available vocabulary for tagging content at that service. The agent is configured to access the one or more data repositories to load a first set of tags corresponding a user-specified service and a user-specified role, display the first set of tags to the user, and to communicate with the user-specified service to post tags selected by the user from the first set of tags to content at the user-specified service.