This Master Thesis has the objective to present a possible solution, using the Blockchain, to solve the fact that Mastodon social network does not support the portability of profiles. Mastodon is one of the most famous DOSN - Decentralized Online Social Network, free, open source, that offers a microblogging service as Twitter. Mastodon supports the interoperability and portability of data across sites, using the ActivityPub open protocol. This allows users connected to one site to follow the users connected to other sites, and to share posts across communities, but if for some reasons, a user decides to migrate to another instance, he/she has to recreate a new account on the new instance with, for example, the unpleasant consequence of loss of followers.