Techniques for authenticating a user may be described. In particular, a network-based document may be provided to a computing system of a user. The network-based document may include code and an identifier of another network-based document. The code may be configured to, upon execution, determine whether the other network-based document was accessed prior to providing the network-based document to the computing system. The other network-based document may be accessible to the user based on an identifier of the user. An indication that the other network-based document was accessed may be determined. For example, the indication may be received from the computing system based on an execution of the code at the computing system. The user may be authenticated based on the indication.