Disclosed are various embodiments for managing security credentials. In one embodiment, network content for a network site is obtained in response to a user request. A connection with a remote computing device that stores and manages security credentials for accessing network sites is authenticated using a master security credential and answers to knowledge-based questions. A security credential associated with the network site is provided to the client from the remote computing device based at least in part on the answers. Access to the network site is authenticated according to the security credential.