Obtaining and/or validating user credentials at client devices is described. This disclosure describes methods of generating representations of credentials for groups of users or for individuals. Representations for these credentials can be managed by a server or collection of servers, and distributed to appropriate users' client devices. These representations can then be outputted for evaluation by a credential authority, who confirms that the credential possessed by a given user is valid. A credential authority may be a person and/or a device that validates a credential.