What is Pleroma?
Pleroma is a free, federated social networking server built on open protocols. It is compatible with GNU Social, Mastodon, and many other ActivityPub and OStatus implementations.
The project consists of several components: Pleroma is the server implementation, and comes bundled with PleromaFE, the default frontend. Other useful utilities are also provided, such as an ActivityPub relay.
For a friendly introduction to Pleroma and the Fediverse, read What is Pleroma?
Comments and Reviews
Said about Pleroma as an alternative
Interface similar to Twitter, interacts with the Fediverse, better moderation tools than Mastodon.
It supports other open source alternatives to Mastodon such as OStatus
Pleroma is part of the OStatus fediverse and the ActivityPub fediverse. Your service is only one out of many, and you can interact with users running SocialHome, Mastodon, Pleroma, PixelFed, PeerTube and other services, and like and comment on their content. If you don't like how your service is run, you can run your own and still be part of the same networks.