Chapeau is a Python-based ActivityPub server, written in Django. It implements ActivityPub and a subset of the Mastodon API.
In the past it has also been known as un_chapeau, and as kepi (one of the submodules).
Repository: https://gitlab.com/marnanel/chapeau/ – also mirrored on github.
Installation guide: https://gitlab.com/marnanel/chapeau/blob/master/docs/installation.md
Demo site: None at present.