Mastodon

Mastodon is an open source microblogging service built as a federated social network. Instead of one central company, anyone with the technical knowledge can run a server where people register, much like email providers. Servers talk to each other over the open ActivityPub protocol, so you can follow and interact with accounts hosted elsewhere.

Because Mastodon is self-hosted open source software, the project is not necessarily European, and where your data lives depends on the server you join. Many servers are operated and hosted in Europe, some of them on renewable energy, and choosing one of those gives you a European alternative to the American social networks.