A server system maintains data indicative of credentials held by multiple different users. Each of the credentials has been issued by a credential granting authority that is separate from an entity that operates the server system. The server system receives selection data that indicates how credential data of a first user is to be made available to other users. Based on the selection data, the server system stores availability data that indicates how credential data of the first user is to be made available to the other users. The server system also maintains a location of a mobile computing device associated with the first user and, based on the availability data and the location, provides, to at least a second user, information about at least one credential held by the first user in association with an indication of the location.