mastodon.online is one of the many independent Mastodon servers you can use to participate in the fediverse.
A newer server operated by the Mastodon gGmbH non-profit

Server stats:

12K
active users

We're coming to the point where decentralized social media contains the only structures we're going to have left that aren't completely controlled by hard-right interests

The one centralized holdout is Bluesky, which means either that's going to need to be decentralized, or it's going to be the next right-wing target over this year probably