cal.com : Open source meeting scheduling tool. Send a link, let others book a slot. Calendly alternative.
Postal : Postal is a complete and fully featured mail server for use by websites & web servers. Think Sendgrid, Mailgun or Postmark but open source and ready f...
Gitea : Gitea is a community managed fork of Gogs, lightweight code hosting solution written in Go and published under the MIT license.
Zulip : Powerful slack-like open source group chat
pump.io : Social server with an ActivityStreams API. It's a stream server that does most of what people really want from a social network.
