Abstract: Online social networks play an important role in everyday life for many people. However, only a few specialized companies offer services and resources that support social networks. This could expose users to undesired publicity and make them vulnerable to information control and censorship. HorNet is a decentralized alternative implementation of a microblogging social network that depends solely on user-provided computational resources. With the service load distributed across all users, each one must contribute only a small amount of resources, and the social network can remain free and under members' control.