Concourse - Pipeline-based CI system written in Go

Meetup - Helps groups of people with shared interests plan events and facilitates off line group meetings in various localities around the world.

Alkarta - Find happenings in your city.

Eventbrite - Discover Great Events or Create Your Own & Sell Tickets

Bookaspace - The easy way to book your next rehearsal space!

Calendify - Calendify is an event community where you can share, publish, and subscribe to event calendars. It helps you to stay informed about what you are interested in and what is yet to come.