Takahē looks neat!
https://github.com/jointakahe/takahe
An experimental Fediverse server for microblogging/"toots". Not fully functional yet - we're still working towards a 1.0!
Current version: 0.5.0
Key features:
Multiple domain support
Multiple identities per user (and can be shared between users)
Desktop, mobile and PWA-compatible web UI (with minimal JavaScript)
Easy deployment (web worker, background worker, and one database)
For more background and information, see jointakahe.org.