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

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.

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

Iventlist - Create an app for your event in minutes 🎟️

Bigtent - BigTent is a web-based organization and communication portal for groups.

Meetup for iOS and Android - Discover groups that are all about the things you love