Presenting Managed Security Credentials to Network Sites

Disclosed are various embodiments for providing managed security credentials to network sites for authentication. Multiple accounts of a user are maintained for multiple network sites. A secured resource of a network site is to be accessed by a computing device. One of the accounts is identified according to a domain name of the network site. The account is associated with a different network site having a different domain name from the domain name. The computing device is automatically authenticated with the network site using a security credential associated with the account.