Pleroma

Pleroma is the top ten most popular software services on the fediverse, based on registered users.

It is social networking software compatible with other Fediverse software such as Misskey, Pixelfed, Mastodon and many others.

It defines itself as “general Twitter-style social media”, but supports long post at 5,000 characters – this is easily changed on a per server basis. It has a simple, adjustable front-end, and included a live chat service with everyone on the same server.